Chi-Square Distribution: A distribution in which a variable is distributed like the sum of the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another.IndiaCross-Sectional Studies: Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time. This contrasts with LONGITUDINAL STUDIES which are followed over a period of time.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Retrospective Studies: Studies used to test etiologic hypotheses in which inferences about an exposure to putative causal factors are derived from data relating to characteristics of persons under study or to events or experiences in their past. The essential feature is that some of the persons under study have the disease or outcome of interest and their characteristics are compared with those of unaffected persons.Prevalence: The total number of cases of a given disease in a specified population at a designated time. It is differentiated from INCIDENCE, which refers to the number of new cases in the population at a given time.TurkeyLeast-Squares Analysis: A principle of estimation in which the estimates of a set of parameters in a statistical model are those quantities minimizing the sum of squared differences between the observed values of a dependent variable and the values predicted by the model.Logistic Models: Statistical models which describe the relationship between a qualitative dependent variable (that is, one which can take only certain discrete values, such as the presence or absence of a disease) and an independent variable. A common application is in epidemiology for estimating an individual's risk (probability of a disease) as a function of a given risk factor.Risk Factors: An aspect of personal behavior or lifestyle, environmental exposure, or inborn or inherited characteristic, which, on the basis of epidemiologic evidence, is known to be associated with a health-related condition considered important to prevent.Health Knowledge, Attitudes, Practice: Knowledge, attitudes, and associated behaviors which pertain to health-related topics such as PATHOLOGIC PROCESSES or diseases, their prevention, and treatment. This term refers to non-health workers and health workers (HEALTH PERSONNEL).Age Factors: Age as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or the effect of a circumstance. It is used with human or animal concepts but should be differentiated from AGING, a physiological process, and TIME FACTORS which refers only to the passage of time.Prospective Studies: Observation of a population for a sufficient number of persons over a sufficient number of years to generate incidence or mortality rates subsequent to the selection of the study group.Treatment Outcome: Evaluation undertaken to assess the results or consequences of management and procedures used in combating disease in order to determine the efficacy, effectiveness, safety, and practicability of these interventions in individual cases or series.Sex Factors: Maleness or femaleness as a constituent element or influence contributing to the production of a result. It may be applicable to the cause or effect of a circumstance. It is used with human or animal concepts but should be differentiated from SEX CHARACTERISTICS, anatomical or physiological manifestations of sex, and from SEX DISTRIBUTION, the number of males and females in given circumstances.Rural Population: The inhabitants of rural areas or of small towns classified as rural.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Follow-Up Studies: Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease.Socioeconomic Factors: Social and economic factors that characterize the individual or group within the social structure.Case-Control Studies: Studies which start with the identification of persons with a disease of interest and a control (comparison, referent) group without the disease. The relationship of an attribute to the disease is examined by comparing diseased and non-diseased persons with regard to the frequency or levels of the attribute in each group.Prognosis: A prediction of the probable outcome of a disease based on a individual's condition and the usual course of the disease as seen in similar situations.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Tai Ji: One of the MARTIAL ARTS and also a form of meditative exercise using methodically slow circular stretching movements and positions of body balance.Severity of Illness Index: Levels within a diagnostic group which are established by various measurement criteria applied to the seriousness of a patient's disorder.Cohort Studies: Studies in which subsets of a defined population are identified. These groups may or may not be exposed to factors hypothesized to influence the probability of the occurrence of a particular disease or other outcome. Cohorts are defined populations which, as a whole, are followed in an attempt to determine distinguishing subgroup characteristics.Digestion: The process of breakdown of food for metabolism and use by the body.Animal Feed: Foodstuff used especially for domestic and laboratory animals, or livestock.Rumen: The first stomach of ruminants. It lies on the left side of the body, occupying the whole of the left side of the abdomen and even stretching across the median plane of the body to the right side. It is capacious, divided into an upper and a lower sac, each of which has a blind sac at its posterior extremity. The rumen is lined by mucous membrane containing no digestive glands, but mucus-secreting glands are present in large numbers. Coarse, partially chewed food is stored and churned in the rumen until the animal finds circumstances convenient for rumination. When this occurs, little balls of food are regurgitated through the esophagus into the mouth, and are subjected to a second more thorough mastication, swallowed, and passed on into other parts of the compound stomach. (From Black's Veterinary Dictionary, 17th ed)Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Reproducibility of Results: The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Models, Statistical: Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Animal Nutritional Physiological Phenomena: Nutritional physiology of animals.Exodeoxyribonuclease V: An ATP-dependent exodeoxyribonuclease that cleaves in either the 5'- to 3'- or the 3'- to 5'-direction to yield 5'-phosphooligonucleotides. It is primarily found in BACTERIA.Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Poaceae: A large family of narrow-leaved herbaceous grasses of the order Cyperales, subclass Commelinidae, class Liliopsida (monocotyledons). Food grains (EDIBLE GRAIN) come from members of this family. RHINITIS, ALLERGIC, SEASONAL can be induced by POLLEN of many of the grasses.Fatty Acids, Volatile: Short-chain fatty acids of up to six carbon atoms in length. They are the major end products of microbial fermentation in the ruminant digestive tract and have also been implicated in the causation of neurological diseases in humans.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Mathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Models, Theoretical: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Random Allocation: A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects.VietnamFermentation: Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.Data Interpretation, Statistical: Application of statistical procedures to analyze specific observed or assumed facts from a particular study.Regression Analysis: Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.Sensitivity and Specificity: Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Silage: Fodder converted into succulent feed for livestock through processes of anaerobic fermentation (as in a silo).Linear Models: Statistical models in which the value of a parameter for a given value of a factor is assumed to be equal to a + bx, where a and b are constants. The models predict a linear regression.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Zea mays: A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.Genotype: The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.Diet: Regular course of eating and drinking adopted by a person or animal.Discriminant Analysis: A statistical analytic technique used with discrete dependent variables, concerned with separating sets of observed values and allocating new values. It is sometimes used instead of regression analysis.Eating: The consumption of edible substances.Dietary Fiber: The remnants of plant cell walls that are resistant to digestion by the alimentary enzymes of man. It comprises various polysaccharides and lignins.Models, Genetic: Theoretical representations that simulate the behavior or activity of genetic processes or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Medicago sativa: A plant species of the family FABACEAE widely cultivated for ANIMAL FEED.Spectroscopy, Near-Infrared: A noninvasive technique that uses the differential absorption properties of hemoglobin and myoglobin to evaluate tissue oxygenation and indirectly can measure regional hemodynamics and blood flow. Near-infrared light (NIR) can propagate through tissues and at particular wavelengths is differentially absorbed by oxygenated vs. deoxygenated forms of hemoglobin and myoglobin. Illumination of intact tissue with NIR allows qualitative assessment of changes in the tissue concentration of these molecules. The analysis is also used to determine body composition.Signal Processing, Computer-Assisted: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.Principal Component Analysis: Mathematical procedure that transforms a number of possibly correlated variables into a smaller number of uncorrelated variables called principal components.Dietary Proteins: Proteins obtained from foods. They are the main source of the ESSENTIAL AMINO ACIDS.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Chromium Compounds: Inorganic compounds that contain chromium as an integral part of the molecule.Statistics as Topic: The science and art of collecting, summarizing, and analyzing data that are subject to random variation. The term is also applied to the data themselves and to the summarization of the data.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Multivariate Analysis: A set of techniques used when variation in several variables has to be studied simultaneously. In statistics, multivariate analysis is interpreted as any analytic method that allows simultaneous study of two or more dependent variables.Calibration: Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output.Nutritive Value: An indication of the contribution of a food to the nutrient content of the diet. This value depends on the quantity of a food which is digested and absorbed and the amounts of the essential nutrients (protein, fat, carbohydrate, minerals, vitamins) which it contains. This value can be affected by soil and growing conditions, handling and storage, and processing.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Molasses: The syrup remaining after sugar is crystallized out of SUGARCANE or sugar beet juice. It is also used in ANIMAL FEED, and in a fermented form, is used to make industrial ETHYL ALCOHOL and ALCOHOLIC BEVERAGES.Quantitative Structure-Activity Relationship: A quantitative prediction of the biological, ecotoxicological or pharmaceutical activity of a molecule. It is based upon structure and activity information gathered from a series of similar compounds.Soybeans: An annual legume. The SEEDS of this plant are edible and used to produce a variety of SOY FOODS.Breeding: The production of offspring by selective mating or HYBRIDIZATION, GENETIC in animals or plants.Software: Sequential operating programs and data which instruct the functioning of a digital computer.ChitinasePublic Facilities: An area of recreation or hygiene for use by the public.Image Interpretation, Computer-Assisted: Methods developed to aid in the interpretation of ultrasound, radiographic images, etc., for diagnosis of disease.Gene Frequency: The proportion of one particular in the total of all ALLELES for one genetic locus in a breeding POPULATION.China: A country spanning from central Asia to the Pacific Ocean.United StatesFood Handling: Any aspect of the operations in the preparation, processing, transport, storage, packaging, wrapping, exposure for sale, service, or delivery of food.Freeze Fracturing: Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.Equipment Design: Methods of creating machines and devices.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Exodeoxyribonucleases: A family of enzymes that catalyze the exonucleolytic cleavage of DNA. It includes members of the class EC 3.1.11 that produce 5'-phosphomonoesters as cleavage products.Predictive Value of Tests: In screening and diagnostic tests, the probability that a person with a positive test is a true positive (i.e., has the disease), is referred to as the predictive value of a positive test; whereas, the predictive value of a negative test is the probability that the person with a negative test does not have the disease. Predictive value is related to the sensitivity and specificity of the test.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Normal Distribution: Continuous frequency distribution of infinite range. Its properties are as follows: 1, continuous, symmetrical distribution with both tails extending to infinity; 2, arithmetic mean, mode, and median identical; and 3, shape completely determined by the mean and standard deviation.Photic Stimulation: Investigative technique commonly used during ELECTROENCEPHALOGRAPHY in which a series of bright light flashes or visual patterns are used to elicit brain activity.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.X-Ray Diffraction: The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Kinetics: The rate dynamics in chemical or physical systems.Congenital Hyperinsulinism: A familial, nontransient HYPOGLYCEMIA with defects in negative feedback of GLUCOSE-regulated INSULIN release. Clinical phenotypes include HYPOGLYCEMIA; HYPERINSULINEMIA; SEIZURES; COMA; and often large BIRTH WEIGHT. Several sub-types exist with the most common, type 1, associated with mutations on an ATP-BINDING CASSETTE TRANSPORTERS (subfamily C, member 8).Amino Acids: Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.Pattern Recognition, Visual: Mental process to visually perceive a critical number of facts (the pattern), such as characters, shapes, displays, or designs.Likelihood Functions: Functions constructed from a statistical model and a set of observed data which give the probability of that data for various values of the unknown model parameters. Those parameter values that maximize the probability are the maximum likelihood estimates of the parameters.Sheep: Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.Factor Analysis, Statistical: A set of statistical methods for analyzing the correlations among several variables in order to estimate the number of fundamental dimensions that underlie the observed data and to describe and measure those dimensions. It is used frequently in the development of scoring systems for rating scales and questionnaires.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Alleles: Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.Duodenum: The shortest and widest portion of the SMALL INTESTINE adjacent to the PYLORUS of the STOMACH. It is named for having the length equal to about the width of 12 fingers.Neural Networks (Computer): A computer architecture, implementable in either hardware or software, modeled after biological neural networks. Like the biological system in which the processing capability is a result of the interconnection strengths between arrays of nonlinear processing nodes, computerized neural networks, often called perceptrons or multilayer connectionist models, consist of neuron-like units. A homogeneous group of units makes up a layer. These networks are good at pattern recognition. They are adaptive, performing tasks by example, and thus are better for decision-making than are linear learning machines or cluster analysis. They do not require explicit programming.Starch: Any of a group of polysaccharides of the general formula (C6-H10-O5)n, composed of a long-chain polymer of glucose in the form of amylose and amylopectin. It is the chief storage form of energy reserve (carbohydrates) in plants.Polymorphism, Genetic: The regular and simultaneous occurrence in a single interbreeding population of two or more discontinuous genotypes. The concept includes differences in genotypes ranging in size from a single nucleotide site (POLYMORPHISM, SINGLE NUCLEOTIDE) to large nucleotide sequences visible at a chromosomal level.Image Enhancement: Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.Genetic Predisposition to Disease: A latent susceptibility to disease at the genetic level, which may be activated under certain conditions.Contrast Sensitivity: The ability to detect sharp boundaries (stimuli) and to detect slight changes in luminance at regions without distinct contours. Psychophysical measurements of this visual function are used to evaluate visual acuity and to detect eye disease.Monte Carlo Method: In statistics, a technique for numerically approximating the solution of a mathematical problem by studying the distribution of some random variable, often generated by a computer. The name alludes to the randomness characteristic of the games of chance played at the gambling casinos in Monte Carlo. (From Random House Unabridged Dictionary, 2d ed, 1993)Feces: Excrement from the INTESTINES, containing unabsorbed solids, waste products, secretions, and BACTERIA of the DIGESTIVE SYSTEM.Nonlinear Dynamics: The study of systems which respond disproportionately (nonlinearly) to initial conditions or perturbing stimuli. Nonlinear systems may exhibit "chaos" which is classically characterized as sensitive dependence on initial conditions. Chaotic systems, while distinguished from more ordered periodic systems, are not random. When their behavior over time is appropriately displayed (in "phase space"), constraints are evident which are described by "strange attractors". Phase space representations of chaotic systems, or strange attractors, usually reveal fractal (FRACTALS) self-similarity across time scales. Natural, including biological, systems often display nonlinear dynamics and chaos.Magnetic Resonance Imaging: Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Mathematical Computing: Computer-assisted interpretation and analysis of various mathematical functions related to a particular problem.Polymorphism, Single Nucleotide: A single nucleotide variation in a genetic sequence that occurs at appreciable frequency in the population.Size Perception: The sensory interpretation of the dimensions of objects.Solutions: The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)Probability: The study of chance processes or the relative frequency characterizing a chance process.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Weight Gain: Increase in BODY WEIGHT over existing weight.Fourier Analysis: Analysis based on the mathematical function first formulated by Jean-Baptiste-Joseph Fourier in 1807. The function, known as the Fourier transform, describes the sinusoidal pattern of any fluctuating pattern in the physical world in terms of its amplitude and its phase. It has broad applications in biomedicine, e.g., analysis of the x-ray crystallography data pivotal in identifying the double helical nature of DNA and in analysis of other molecules, including viruses, and the modified back-projection algorithm universally used in computerized tomography imaging, etc. (From Segen, The Dictionary of Modern Medicine, 1992)Psychophysics: The science dealing with the correlation of the physical characteristics of a stimulus, e.g., frequency or intensity, with the response to the stimulus, in order to assess the psychologic factors involved in the relationship.Toxocara: A genus of ascarid nematodes commonly parasitic in the intestines of cats and dogs.Ileum: The distal and narrowest portion of the SMALL INTESTINE, between the JEJUNUM and the ILEOCECAL VALVE of the LARGE INTESTINE.Phantoms, Imaging: Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)Motion: Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.Dietary Supplements: Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients. Dietary supplements can include macronutrients, such as proteins, carbohydrates, and fats; and/or MICRONUTRIENTS, such as VITAMINS; MINERALS; and PHYTOCHEMICALS.Postural Balance: A POSTURE in which an ideal body mass distribution is achieved. Postural balance provides the body carriage stability and conditions for normal functions in stationary position or in movement, such as sitting, standing, or walking.Electricity: The physical effects involving the presence of electric charges at rest and in motion.ComputersHordeum: A plant genus of the family POACEAE. The EDIBLE GRAIN, barley, is widely used as food.Reference Values: The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.Artifacts: Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.Double-Blind Method: A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment.Thermodynamics: A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)Lighting: The illumination of an environment and the arrangement of lights to achieve an effect or optimal visibility. Its application is in domestic or in public settings and in medical and non-medical environments.Signal-To-Noise Ratio: The comparison of the quantity of meaningful data to the irrelevant or incorrect data.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Corneal Topography: The measurement of curvature and shape of the anterior surface of the cornea using techniques such as keratometry, keratoscopy, photokeratoscopy, profile photography, computer-assisted image processing and videokeratography. This measurement is often applied in the fitting of contact lenses and in diagnosing corneal diseases or corneal changes including keratoconus, which occur after keratotomy and keratoplasty.Optical Illusions: An illusion of vision usually affecting spatial relations.Photometry: Measurement of the various properties of light.Equipment Failure Analysis: The evaluation of incidents involving the loss of function of a device. These evaluations are used for a variety of purposes such as to determine the failure rates, the causes of failures, costs of failures, and the reliability and maintainability of devices.Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.Intramolecular Lyases: Enzymes of the isomerase class that catalyze reactions in which a group can be regarded as eliminated from one part of a molecule, leaving a double bond, while remaining covalently attached to the molecule. (From Enzyme Nomenclature, 1992) EC 5.5.Animal Husbandry: The science of breeding, feeding and care of domestic animals; includes housing and nutrition.Mastication: The act and process of chewing and grinding food in the mouth.Transducers: Any device or element which converts an input signal into an output signal of a different form. Examples include the microphone, phonographic pickup, loudspeaker, barometer, photoelectric cell, automobile horn, doorbell, and underwater sound transducer. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Incidence: The number of new cases of a given disease during a given period in a specified population. It also is used for the rate at which new events occur in a defined population. It is differentiated from PREVALENCE, which refers to all cases, new or old, in the population at a given time.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Support Vector Machines: Learning algorithms which are a set of related supervised computer learning methods that analyze data and recognize patterns, and used for classification and regression analysis.Head Injuries, Closed: Traumatic injuries to the cranium where the integrity of the skull is not compromised and no bone fragments or other objects penetrate the skull and dura mater. This frequently results in mechanical injury being transmitted to intracranial structures which may produce traumatic brain injuries, hemorrhage, or cranial nerve injury. (From Rowland, Merritt's Textbook of Neurology, 9th ed, p417)Crystallography, X-Ray: The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Cereals: Seeds from grasses (POACEAE) which are important in the diet.Stomach, RuminantInfant, Newborn: An infant during the first month after birth.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Visual Perception: The selecting and organizing of visual stimuli based on the individual's past experience.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Metabolomics: The systematic identification and quantitation of all the metabolic products of a cell, tissue, organ, or organism under varying conditions. The METABOLOME of a cell or organism is a dynamic collection of metabolites which represent its net response to current conditions.Body Mass Index: An indicator of body density as determined by the relationship of BODY WEIGHT to BODY HEIGHT. BMI=weight (kg)/height squared (m2). BMI correlates with body fat (ADIPOSE TISSUE). Their relationship varies with age and gender. For adults, BMI falls into these categories: below 18.5 (underweight); 18.5-24.9 (normal); 25.0-29.9 (overweight); 30.0 and above (obese). (National Center for Health Statistics, Centers for Disease Control and Prevention)Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Corneal Wavefront Aberration: Asymmetries in the topography and refractive index of the corneal surface that affect visual acuity.Computational Biology: A field of biology concerned with the development of techniques for the collection and manipulation of biological data, and the use of such data to make biological discoveries or predictions. This field encompasses all computational methods and theories for solving biological problems including manipulation of models and datasets.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Adipokines: Polypeptides produced by the ADIPOCYTES. They include LEPTIN; ADIPONECTIN; RESISTIN; and many cytokines of the immune system, such as TUMOR NECROSIS FACTOR-ALPHA; INTERLEUKIN-6; and COMPLEMENT FACTOR D (also known as ADIPSIN). They have potent autocrine, paracrine, and endocrine functions.Risk Assessment: The qualitative or quantitative estimation of the likelihood of adverse effects that may result from exposure to specified health hazards or from the absence of beneficial influences. (Last, Dictionary of Epidemiology, 1988)Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Biophysical Phenomena: The physical characteristics and processes of biological systems.Cross-Over Studies: Studies comparing two or more treatments or interventions in which the subjects or patients, upon completion of the course of one treatment, are switched to another. In the case of two treatments, A and B, half the subjects are randomly allocated to receive these in the order A, B and half to receive them in the order B, A. A criticism of this design is that effects of the first treatment may carry over into the period when the second is given. (Last, A Dictionary of Epidemiology, 2d ed)Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Facility Design and Construction: Architecture, exterior and interior design, and construction of facilities other than hospitals, e.g., dental schools, medical schools, ambulatory care clinics, and specified units of health care facilities. The concept also includes architecture, design, and construction of specialized contained, controlled, or closed research environments including those of space labs and stations.Population Density: Number of individuals in a population relative to space.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Movement: The act, process, or result of passing from one place or position to another. It differs from LOCOMOTION in that locomotion is restricted to the passing of the whole body from one place to another, while movement encompasses both locomotion but also a change of the position of the whole body or any of its parts. Movement may be used with reference to humans, vertebrate and invertebrate animals, and microorganisms. Differentiate also from MOTOR ACTIVITY, movement associated with behavior.Physical Phenomena: The entities of matter and energy, and the processes, principles, properties, and relationships describing their nature and interactions.Pattern Recognition, Automated: In INFORMATION RETRIEVAL, machine-sensing or identification of visible patterns (shapes, forms, and configurations). (Harrod's Librarians' Glossary, 7th ed)Seasons: Divisions of the year according to some regularly recurrent phenomena usually astronomical or climatic. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Pilot Projects: Small-scale tests of methods and procedures to be used on a larger scale if the pilot study demonstrates that these methods and procedures can work.Quality of Life: A generic concept reflecting concern with the modification and enhancement of life attributes, e.g., physical, political, moral and social environment; the overall condition of a human life.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Spectroscopy, Fourier Transform Infrared: A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.Scattering, Radiation: The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Phenotype: The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.Sensory Thresholds: The minimum amount of stimulus energy necessary to elicit a sensory response.Martial Arts: Activities in which participants learn self-defense mainly through the use of hand-to-hand combat. Judo involves throwing an opponent to the ground while karate (which includes kung fu and tae kwon do) involves kicking and punching an opponent.Numerical Analysis, Computer-Assisted: Computer-assisted study of methods for obtaining useful quantitative solutions to problems that have been expressed mathematically.Survival Analysis: A class of statistical procedures for estimating the survival function (function of time, starting with a population 100% well at a given time and providing the percentage of the population still well at later times). The survival analysis is then used for making inferences about the effects of treatments, prognostic factors, exposures, and other covariates on the function.Feeding Behavior: Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.Gastrointestinal Transit: Passage of food (sometimes in the form of a test meal) through the gastrointestinal tract as measured in minutes or hours. The rate of passage through the intestine is an indicator of small bowel function.Imaging, Three-Dimensional: The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.Psychometrics: Assessment of psychological variables by the application of mathematical procedures.Recombination, Genetic: Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses.Genetic Markers: A phenotypically recognizable genetic trait which can be used to identify a genetic locus, a linkage group, or a recombination event.

Sex differences in the effects of early neocortical injury on neuronal size distribution of the medial geniculate nucleus in the rat are mediated by perinatal gonadal steroids. (1/11846)

Freezing injury to the cortical plate of rats induces cerebrocortical microgyria and, in males but not females, a shift toward greater numbers of small neurons in the medial geniculate nucleus (MGN). The purpose of the current study was to examine a hormonal basis for this sex difference. Cross-sectional neuronal areas of the MGN were measured in male rats, untreated female rats and female rats treated perinatally with testosterone propionate, all of which had received either neonatal cortical freezing or sham injury. Both male and androgenized female rats with microgyria had significantly smaller MGN neurons when compared to their sham-operated counterparts, whereas untreated females with microgyria did not. These differences were also reflected in MGN neuronal size distribution: both male and androgenized female rats with microgyria had more small and fewer large neurons in their MGN in comparison to shams, while there was no difference in MGN neuronal size distribution between lesioned and sham females. These findings suggest that perinatal gonadal steroids mediate the sex difference in thalamic response to induction of microgyria in the rat cortex.  (+info)

Natural history of dysplasia of the uterine cervix. (2/11846)

BACKGROUND: A historical cohort of Toronto (Ontario, Canada) women whose Pap smear histories were recorded at a major cytopathology laboratory provided the opportunity to study progression and regression of cervical dysplasia in an era (1962-1980) during which cervical squamous lesions were managed conservatively. METHODS: Actuarial and Cox's survival analyses were used to estimate the rates and relative risks of progression and regression of mild (cervical intraepithelial neoplasia 1 [CIN1]) and moderate (CIN2) dysplasias. In addition, more than 17,000 women with a history of Pap smears between 1970 and 1980 inclusive and who were diagnosed as having mild, moderate, or severe dysplasia were linked to the Ontario Cancer Registry for the outcome of any subsequent cervical cancers occurring through 1989. RESULTS: Both mild and moderate dysplasias were more likely to regress than to progress. The risk of progression from mild to severe dysplasia or worse was only 1% per year, but the risk of progression from moderate dysplasia was 16% within 2 years and 25% within 5 years. Most of the excess risk of cervical cancer for severe and moderate dysplasias occurred within 2 years of the initial dysplastic smear. After 2 years, in comparison with mild dysplasia, the relative risks for progression from severe or moderate dysplasia to cervical cancer in situ or worse was 4.2 (95% confidence interval [CI] = 3.0-5.7) and 2.5 (95% CI = 2.2-3.0), respectively. CONCLUSION: The risk of progression for moderate dysplasia was intermediate between the risks for mild and severe dysplasia; thus, the moderate category may represent a clinically useful distinction. The majority of untreated mild dysplasias were recorded as regressing to yield a normal smear within 2 years.  (+info)

Low-dose combination therapy as first-line hypertension treatment for blacks and nonblacks. (3/11846)

To assess the efficacy and safety of bisoprolol/6.25-mg hydrochlorothiazide (HCTZ), amlodipine, and enalapril in black and nonblack patients, data from two comparative studies were pooled and subgroup analyses performed. Both studies had similar designs and included all three active treatments. The second study also included a placebo group. Subjects (n = 541) with a sitting diastolic blood pressure of 95-114 mmHg were titrated to achieve a diastolic blood pressure < or = 90 mmHg. The studies included 114 blacks and 427 nonblacks. Results of an intention-to-treat analysis of mean change from baseline after 12 weeks of treatment showed the following: 1) blood pressure was significantly lowered by all three active drugs compared with baseline or placebo; 2) in blacks, bisoprolol/6.25-mg HCTZ resulted in significantly greater reductions of systolic and diastolic blood pressure than enalapril or placebo, but was not significantly different from amlodipine; 3) in nonblacks, bisoprolol/6.25-mg HCTZ resulted in significantly greater reduction of diastolic blood pressure than amlodipine, enalapril, or placebo. The placebo-corrected change in blood pressure was greater for blacks than whites on the bisoprolol/6.25-mg HCTZ combination, but this was not statistically significant. Bisoprolol/6.25-mg HCTZ controlled diastolic blood pressure to < or = 90 mmHg in significantly more patients than enalapril or placebo in blacks and nonblacks. The difference in control rates was not significant versus amlodipine. The incidence of drug-related adverse events was similar between treatments; however, bisoprolol/6.25-mg HCTZ had a lower discontinuation rate due to lack of blood pressure control or adverse experiences in both blacks and nonblacks.  (+info)

Extent and severity of atherosclerotic involvement of the aortic valve and root in familial hypercholesterolaemia. (4/11846)

OBJECTIVE: To compare the frequency of valvar and supravalvar aortic stenosis in homozygous and heterozygous familial hypercholesterolaemia (FH). DESIGN: Analysis of life time cholesterol exposure and prevalence of aortic atherosclerosis in 84 consecutive cases attending a lipid clinic. SETTING: A tertiary referral centre in London. PATIENTS: Outpatients with FH (six homozygous, 78 heterozygous). INTERVENTIONS: Maintenance of lipid lowering treatment. MAIN OUTCOME MEASURES: Calculated cholesterol x years score (CYS) and echocardiographic measurement of aortic root diameter, aortic valve thickness, and transaortic gradient. RESULTS: Four homozygotes with a mean (SD) CYS of 387 (124) mmol/1 x years had severe aortic stenosis (treatment started after seven years of age), whereas the other two had echocardiographic evidence of supravalvar thickening but no aortic valve stenosis (treatment started before three years of age). On multivariate analysis, mean transaortic gradient correlated significantly with CYS (mean = 523 (175) mmol/1 x years) in heterozygotes (p = 0.0001), but only two had severe aortic valve and root involvement. CONCLUSIONS: In patients with familial hypercholesterolaemia, aortic stenosis is common in homozygotes, and aortic root involvement is always present despite the lower CYS than in heterozygotes. It appears to be determined by short term exposure to high cholesterol concentrations in early life. Conversely, aortic root and valve involvement are rare in heterozygotes and occur only with severe, prolonged hypercholesterolaemia, possibly accelerating age related degenerative effects.  (+info)

Amino acid composition of protein termini are biased in different manners. (5/11846)

An exhaustive statistical analysis of the amino acid sequences at the carboxyl (C) and amino (N) termini of proteins and of coding nucleic acid sequences at the 5' side of the stop codons was undertaken. At the N ends, Met and Ala residues are over-represented at the first (+1) position whereas at positions 2 and 5 Thr is preferred. These peculiarities at N-termini are most probably related to the mechanism of initiation of translation (for Met) and to the mechanisms governing the life-span of proteins via regulation of their degradation (for Ala and Thr). We assume that the C-terminal bias facilitates fixation of the C ends on the protein globule by a preference for charged and Cys residues. The terminal biases, a novel feature of protein structure, have to be taken into account when molecular evolution, three-dimensional structure, initiation and termination of translation, protein folding and life-span are concerned. In addition, the bias of protein termini composition is an important feature which should be considered in protein engineering experiments.  (+info)

Prevalence of true vein graft aneurysms: implications for aneurysm pathogenesis. (6/11846)

BACKGROUND: Circumstantial evidence suggests that arterial aneurysms have a different cause than atherosclerosis and may form part of a generalized dilating diathesis. The aim of this study was to compare the rates of spontaneous aneurysm formation in vein grafts performed either for popliteal aneurysms or for occlusive disease. The hypothesis was that if arterial aneurysms form a part of a systemic process, then the rates of vein graft aneurysms should be higher for patients with popliteal aneurysms than for patients with lower limb ischemia caused by atherosclerosis. METHODS: Infrainguinal vein grafting procedures performed from 1990 to 1995 were entered into a prospective audit and graft surveillance program. Aneurysmal change was defined as a focal increase in the graft diameter of 1.5 cm or greater, excluding false aneurysms and dilatations after graft angioplasty. RESULTS: During the study period, 221 grafting procedures were performed in 200 patients with occlusive disease and 24 grafting procedures were performed in 21 patients with popliteal aneurysms. Graft surveillance revealed spontaneous aneurysm formation in 10 of the 24 bypass grafts (42%) for popliteal aneurysms but in only 4 of the 221 grafting procedures (2%) that were performed for chronic lower limb ischemia. CONCLUSION: This study provides further evidence that aneurysmal disease is a systemic process, and this finding has clinical implications for the treatment of popliteal aneurysms.  (+info)

Cryoglobulinaemia and rheumatic manifestations in patients with hepatitis C virus infection. (7/11846)

OBJECTIVES: To investigate the association of cryoglobulinaemia and rheumatic manifestations in Korean patients with hepatitis C virus (HCV) infection. METHODS: Forty nine Korean patients with HCV infection were recruited. The prevalence, concentration, and type of cryoglobulin (by immunofixation), rheumatoid factor (RF), antinuclear antibody (ANA), and various rheumatological symptoms were investigated and HCV genotype was determined by polymerase chain reaction with genotype specific primer. RESULTS: The prevalence of cryoglobulin was 59% in Korean HCV patients and the concentration of cryoglobulin was 9.8 (7.9) g/l (mean (SD)). The type of cryoglobulinaemia was identified in 23 (80%) of 29 HCV patients with cryoglobulinaemia and they were all type III. There were no differences in age, sex, history of operation and transfusion, proportion of liver cirrhosis between the patients with cryoglobulinaemia and those without cryoglobulinaemia. The frequencies of RF and ANA were 14% and 3.4% respectively in HCV patients with cryoglobulinaemia. There was no difference in HCV genotype between the patients with cryoglobulinaemia and those without cryoglobulinaemia. Clinical features of HCV patients were as follows: arthralgia/arthritis (35%), cutaneous manifestation (37%), Raynaud's phenomenon (8%), paresthesia (44%), dry eyes (22%), dry mouth (10%), oral ulcer (33%), and abdominal pain (14%). However, these rheumatological symptoms did not differ between the two groups. CONCLUSION: Although the rheumatological symptoms were not different between HCV patients with and without cryoglobulinaemia, HCV patients showed various rheumatological manifestations. These result suggests that HCV infection could be included as one of the causes in patients with unexplained rheumatological symptoms.  (+info)

Fetal tachycardias: management and outcome of 127 consecutive cases. (8/11846)

OBJECTIVE: To review the management and outcome of fetal tachycardia, and to determine the problems encountered with various treatment protocols. STUDY DESIGN: Retrospective analysis. SUBJECTS: 127 consecutive fetuses with a tachycardia presenting between 1980 and 1996 to a single tertiary centre for fetal cardiology. The median gestational age at presentation was 32 weeks (range 18 to 42). RESULTS: 105 fetuses had a supraventricular tachycardia and 22 had atrial flutter. Overall, 52 fetuses were hydropic and 75 non-hydropic. Prenatal control of the tachycardia was achieved in 83% of treated non-hydropic fetuses compared with 66% of the treated hydropic fetuses. Digoxin monotherapy converted most (62%) of the treated non-hydropic fetuses, and 96% survived through the neonatal period. First line drug treatment for hydropic fetuses was more diverse, including digoxin (n = 5), digoxin plus verapamil (n = 14), and flecainide (n = 27). The response rates to these drugs were 20%, 57%, and 59%, respectively, confirming that digoxin monotherapy is a poor choice for the hydropic fetus. Response to flecainide was faster than to the other drugs. Direct fetal treatment was used in four fetuses, of whom two survived. Overall, 73% (n = 38) of the hydropic fetuses survived. Postnatally, 4% of the non-hydropic group had ECG evidence of pre-excitation, compared with 16% of the hydropic group; 57% of non-hydropic fetuses were treated with long term anti-arrhythmics compared with 79% of hydropic fetuses. CONCLUSIONS: Non-hydropic fetuses with tachycardias have a very good prognosis with transplacental treatment. Most arrhythmias associated with fetal hydrops can be controlled with transplacental treatment, but the mortality in this group is 27%. At present, there is no ideal treatment protocol for these fetuses and a large prospective multicentre trial is required to optimise treatment of both hydropic and non-hydropic fetuses.  (+info)

Definition of Chi-square distribution in the Legal Dictionary - by Free online English dictionary and encyclopedia. What is Chi-square distribution? Meaning of Chi-square distribution as a legal term. What does Chi-square distribution mean in law?
Hello, I am trying to understand some results I got (see below) and any assistance will be greatly appreciated. I have run a number of conditional logit models (with cluster-adjusted robust SEs) and usually, if you get a greater Wald chi-square value, you also get a greater pseudo r-square. But the models below are strange in that the first one has a great pseudo r-square value while the second one has a greater Wald chi-square value. The only thing that changes from one model to the next are the third and fourth variables starting from the bottom (i.e., in the second model, a_lneuclkm and m_lneuclkm have been substituted by a_lneuclmins and m_lneuclmins). Does anyone have any information about how the Wald test statistic is calculated so that I can relate this to how the log-likelihood and the pseudo r-square are calculated (and work out why they might be behaving in this way)? Thanks very much, Lucia. Model 1 . clogit choice commerc100 nostations popdens unemp10 imdincome imdhealth ...
Im trying to see if there is a dependent relationship between whether a school is public or private and its student-teacher ratio. Im not sure if I can use a chi square test for this because there is like a 6 to 1 ratio between the amounts of public and private schools that I have for my data (way more public schools). Can I chi square test still work ...
Determining significance of chi square. If we wish to reject Ho at the .05 level, we will determine if our value of chi square is greater than the critical value of chi square that cuts off the upper 5% of the distribution at our particular degrees of freedom value. If our value of chi square from the formula is greater than the critical value of chi square, we reject Ho and conclude that the obtained frequencies differ from the expected frequencies more than would be predicted by chance. ...
Join Barton Poulson for an in-depth discussion in this video Single categorical variable: One-sample chi-squared test, part of SPSS Statistics Essential Training
A JavaScript that computes Chi-square statistic as a measuring tool and decision criterion for goodness of-fit distributions of observed frequencies.
where L is a matrix of coefficients for the linear hypotheses, and c is a vector of constants. The Wald chi-square statistic for testing ...
Used for comparing frequencies (counts) of nominal or ordinal level data for two samples across two or more subgroups displayed in a crosstabulation table. More common and more flexible than z-tests of proportions ...
Free chi-square distribution calculator computes cumulative probability. Fast, easy, accurate. An online chi-square statistical table. Includes sample problems.
Computes the continuous non-central chi-squared cumulative distribution function (CDF), the probability that a non-central chi-squared-distributed variate takes on a value less than or equal to the quantile of the random variable. A non-central chi-squared variate with k degrees of freedom and nonce
Get Online Statistics Help on chi-square assignment help and chi-square Homework help from best experts of Courseworktutors Inc at affordable prices.
The Chi-Square test of Independence is used to determine if there is a significant relationship between two nominal (categorical) variables.
Solved: I want to integral this function (1-chi-square(x/2,df=10))**5 by the chi-square( x, df=10), so I write the code below. However, the error
Understanding chi-square, regression and ANOVA outputs from spss! Categorical variations and regression, what really matter in the outputs?
I need help identifying variables and conducting t-tests and chi-squared tests and how to use Excel to calculate the data. Identify three continuous and three discrete variables and describe their distribution numerically (e.g.,.
Friedmans test is a nonparametric test for treatment differences in a randomized complete block design. Each block of the design may be a subject or a homogeneous group of subjects. If blocks are groups of subjects, the number of subjects in each block must equal the number of treatments. Treatments are randomly assigned to subjects within each block. If there is one subject per block, then the subjects are repeatedly measured once under each treatment. The order of treatments is randomized for each subject. In this setting, Friedmans test is identical to the ANOVA (row means scores) CMH statistic when the analysis uses rank scores (SCORES=RANK). The three-way table uses subject (or subject group) as the stratifying variable, treatment as the row variable, and response as the column variable. PROC FREQ handles ties by assigning midranks to tied response values. If there are multiple subjects per treatment in each block, the ANOVA CMH statistic is a generalization of Friedmans test. The data ...
A standalone Windows program that calculates the chi-square statistic for 2x2 to 10x10 contingency tables. Also calculates the contingency coefficient, phi, and
1. What is the null and alternative hypothesis to test whether a person?s educational level is dependent or independent of his or her race/gender classification? 2. Looking at the p-value, would you accept or reject the null.
The most unbiased point estimate for the population variance σ2 is the sample-variance (s2) and the point estimate for the population standard deviation σ is the sample standard deviation (s). We use a Chi-square distribution to construct confidence intervals for the variance and standard distribution. If the process or phenomenon we study generates a Normal random variable, then computing the following random variable (for a sample of size n , 1) has a Chi-square distribution ...
Chi-square analysis is a statistical method to calculate the probability that two dichotomous variables within a sample or population are related. This ...
This activity looks at the distribution of heart attacks over the days of the week. It starts out looking at those who are employed, but there is an extra data set that looks at those who are not employed. Comments from participants at our Morro Bay workshop are left in to see the discussion between statisticians and biologists as we try to shape activities that get biologists to think statistically.. Chi-square test. ...
CHI-Squared Test of Independence Minhaz Fahim Zibran Department of Computer Science University of Calgary, Alberta, Canada. Abstract Chi-square (X 2 ) test is a nonparametric
From the image above, it can be seen that the most contributing cells to the Chi-square are Wife/Laundry (7.74%), Wife/Main_meal (4.98%), Husband/Repairs (21.9%), Jointly/Holidays (12.44%).. These cells contribute about 47.06% to the total Chi-square score and thus account for most of the difference between expected and observed values.. This confirms the earlier visual interpretation of the data. As stated earlier, visual interpretation may be complex when the contingency table is very large. In this case, the contribution of one cell to the total Chi-square score becomes a useful way of establishing the nature of dependency ...
Today s lecture Lecture 6: Dichotomous Variables & Chi-square tests Sandy Eckel Dichotomous Variables Comparing two proportions using 2 2 tables Study Designs Relative risks, odds ratios
Non-normal is not a specific distribution. If you really want to know how much difference it would make you must be specific about the distribution - and if you are specific then you can calculate the difference yourself ...
If youre working on any statistical problem involving chi-square SPSS is the program you need. Get to grips with using the versatile and helpful program.
nbsp1.which of following does the term observed frequency refer to?nbspa frequencies computed from the null hypothesisb, Hire Statistics and Probability Expert, Ask Statistics Expert, Assignment Help, Homework Help, Textbooks Solutions
Also called Parrys disease. Plummers disease is the cause of about 5% of cases of hyperthyroidism. It does not usually remit after a course of antithyroid drugs. Plummers condition characterized by marked enlargement of the thyroid gland (goitre), firm thyroid nodules, and mild overproduction of thyroid hormone.. Plummers disease, which usually occurs in older people, is of unknown etiology. Its symptoms resemble those of Graves disease, a condition believed to be an autoimmune disorder.. Also known as Graves disease, thyrotoxicosis, toxic diffuse goiter, toxic nodular goiter and Basedows disease. Hyperthyroidism is a condition marked by excessive production of thyroid hormones that results in multiple-system abnormalities ranging from mild to severe hormonal imbalances.. The physical examination may reveal a rapid and/or irregular heart beat, warm, thin, moist skin over most of the body. Other physical signs which can occur in certain people are eyelid lag, eyelid retraction, abnormal ...
For a correctly specified model, the Pearson chi-square statistic and the deviance, divided by their degrees of freedom, should be approximately equal to one. When their values are much larger than one, the assumption of binomial variability might not be valid and the data are said to exhibit overdispersion. Underdispersion, which results in the ratios being less than one, occurs less often in practice. When fitting a model, there are several problems that can cause the goodness-of-fit statistics to exceed their degrees of freedom. Among these are such problems as outliers in the data, using the wrong link function, omitting important terms from the model, and needing to transform some predictors. These problems should be eliminated before proceeding to use the following methods to correct for overdispersion. ...
The Chi-Square distribution is used in the chi-square tests for goodness of fit of an observed distribution to a theoretical one and the independence of two criteria of classification of qualitative data. It is also used in confidence interval estimation for a population standard deviation of a normal distribution from a sample standard deviation. The Chi-Square distribution is a special case of the Gamma distribution [link to gamma]. PDF ...
This statistic is useful if you have two ordered variables, going from Low to High. They dont need to be interval: all you need to do is order it; in the case of which one is bigger, and which one is smaller. If you have people who are Temp; People who are hourly; exempt employees; profit-sharing; you could code these things as 1,2,3,4, but would it make sense to run a correlation looking for a linear relationship between them? Not really. But it would make sense at a job level, if you were able to put these in a specific order. Take an attitude measure: Strongly Agree (1) ,-? (2) -,Strongly Disagree (3) - there arent necessarily equal intervals here, but what were interested in is whether there is an ordinal trend, such as, "are people higher in the job level more likely to agree? Example 2 In a 2x2 table like in Example 3 what test would you apply? Chi Square Test of Independence. If you ran a χ^2 on this table, ...
is an approximation which is valid only for large values of n, and is therefore only meaningful when calculated from a large number of independent experiments.. In this implementation, the Chi-Square distribution is calculated for the list of values given as argument to the random-test procedure and expressed as an absolute number and a percentage which indicates how frequently a truly random sequence would exceed the value calculated.. The percentage can be interpreted as the degree to which the sequence tested is suspected of being non-random. If the percentage is greater than 99% or less than 1%, the sequence is almost certainly not random. If the percentage is between 99% and 95% or between 1% and 5%, the sequence is suspect. Percentages between 90% and 95% and 5% and 10% indicate the sequence is almost suspect.. ...
When dealing with two categorical variables, a two-way table is a helpful way to display this data. Find out what is a two-way table.
To understand which instruments and symptoms best discriminate episodes, canonical discriminant analyses (CDAs) were conducted. These statistical procedures find patterns of canonical correlation between features that separate scores and items according to a dependent variable. In other words, CDA is a type of regression that allows identification of which items or instruments are better than others to separate groups. Three indexes are used to interpret CDA: chi-square, Wilks lambda, and the standardized canonical coefficient (SCC). The chi-square statistic reveals whether the variable is able to discriminate groups in a significant manner (p < 0.05). Wilks lambda tests the extent to which a variable contributes to discrimination: the closer to 0 the index, the higher the extent to which the variable contributes to separate groups. Finally, the SCC ranks the importance of variables to separate groups; i.e., the higher the coefficient, the more important the variable. SCC and Wilks lambda are ...
The paper presents a new concept of parallel bivariate marginal distribution algorithm using the stepping stone based model of communication with the unidirectional ring topology. The traditional migration of individuals is compared with a newly proposed technique of probability model migration. The idea of the new xBMDA algorithms is to modify the learning of classic probability model (applied in the sequential BMDA). In the first strategy, the adaptive learning of the resident probability model is used. The evaluation of pair dependency, using Pearsons chi-square statistics is influenced by the relevant immigrant pair dependency according to the quality of resident and immigrant subpopulation. In the second proposed strategy, the evaluation metric is applied for the diploid mode of the aggregated resident and immigrant subpopulation. Experimental results show that the proposed adaptive BMDA outperforms the traditional concept of individual migration ...
Methods: This is a prospective study of 119 patients admitted with hip fracture during a 14 month period. Patients were divided into two groups, diabetics (n=19) and non-diabetics (n=100). Information was collected including patient demographics, functional status, medical co-morbidities (using the CCI - Charlson Co-morbidity Index tool), previous history of fractures, vitamin D level and supplementation, fracture type and duration to surgery. Immediate post-operative complications, rate of 30-day mortality and length of rehabilitation stay were analysed and compared between the two groups. The validity of the results was assessed using the Chi-square statistic for categorical variables and the t-test for continuous variables using the Systat program. Results: The mean age was significantly different for each group with diabetics presenting 6 years earlier (age 77.5 versus 83.5, p = 0.03).The CCI score had a bimodal distribution in diabetics. Other baseline characteristics were comparable ...
AIM: To describe the endodontic status amongst middle-aged and elderly women longitudinally and cross-sectionally over 24 years. METHODOLOGY: A random sample of 1462 women 38, 46, 50, 54 and 60 years old, living in Göteborg, Sweden, were sampled in 1968 for medical and dental examinations with a participation rate of 90.1%. The same women were re-examined in 1980 and 1992 together with new 38- and 50-year-old women. The dental examination consisted of questionnaires, clinical and panoramic radiological survey (OPG). The number of teeth, number of root filled teeth (RF) and number of teeth with periapical radiolucencies (PA) were registered. The RF and PA ratios were calculated. Cross-sectional data were analysed by means of anova and longitudinal data by a general linear model for repeated measures. Sample prevalences were compared and statistical inferences were made with the chi-squared test. In all analysis, the confidence interval (CI) regarded mean difference between groups (95% CI). ...
I want to calculate chi square test of goodness of fit to test, Sample coming from Poisson distribution. please copy this script in R & run the script The R script is as follows ########################## start ######################################### No_of_Frouds,- c(4,1,6,9,9,10,2,4,8,2,3,0,1,2,3,1,3,4,5,4,4,4,9,5,4,3,11,8,12,3,10,0,7) N ,- length(No_of_Frouds) # Estimation of Parameter lambda,- sum(No_of_Frouds)/N lambda pmf ,- dpois(i, lambda, log = FALSE) step_function ,- ppois(i, lambda, lower.tail = TRUE, log.p = FALSE) # Chi-Squared Goodness of Fit Test # Ho: The data follow a Poisson distribution Vs H1: Not Ho Frauds ,- c(1:13) counts,- c(2,3,3,5,7,2,1,1,2,3,2,1,1,0) # Observed frequency Expected ,-c(0.251005528,1.224602726,2.987288468,4.85811559,5.925428863,5.7817821 03,4.701348074,3.276697142,1.998288788,1.083247457,0.528493456,0.2344006 79,0.095299266,0.035764993) chisq.test(counts, Expected, simulate.p.value =FALSE, correct = FALSE) ######################### end ...
Preface xiii Part I. Summarizing Data 1. 1. Data Organization 3. 1.1 Introduction 3. 1.2 Consideration of Variables 4. 1.3 Coding 15. 1.4 Data Manipulations 18. 1.5 Conclusion 20. 2. Descriptive Statistics for Categorical Data 33. 2.1 Introduction 33. 2.2 Frequency Tables 35. 2.3 Crosstabulations 37. 2.4 Graphs and Charts 45. 2.5 Conclusion 50. 3. Descriptive Statistics for Continuous Data 63. 3.1 Introduction 63. 3.2 Frequencies 64. 3.3 Measures of Central Tendency 70. 3.4 Measures of Dispersion 73. 3.5 Standardized Scores 79. 3.6 Conclusion 88. Part II. Statistical Tests 101. 4. Evaluating Statistical Significance 103. 4.1 Introduction 103. 4.2 Central Limit Theorem 104. 4.3 Statistical Significance 107. 4.4 The Roles of Hypotheses 115. 4.5 Conclusion 119. 5. The Chi-Square Test: Comparing Category Frequencies 125. 5.1 Introduction 125. 5.2 The Chi-Square Distribution 126. 5.3 Performing Chi-Square Tests 130. 5.4 Post Hoc Testing 143. 5.5 Confidence Intervals 146. 5.6 Explaining Results of the ...
A distribution in which a variable is distributed like the sum of the the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another. ...
The p-value of the test is 8.80310^{-7}, which is less than the significance level alpha = 0.05. We can conclude that the colors are significantly not commonly distributed with a p-value = 8.80310^{-7}. Note that, the chi-square test should be used only when all calculated expected values are greater than 5.. ...
I have a question regarding the relationship between the value of Chi square and df in determining the goodness-of-fit in a model derived from multivariate logistic regression. If the N= 290, Chi square =26.57, p=0.003 in a model with 16 variables (df is not reported), can one tell if this is ...
Since the chi-square test statistic 2.30 does not meet or exceed the critical value of 9.488, you cannot conclude there is a statistically significant difference among the assembly lines in the observed frequencies of defective parts ...
Perform crosstabs with multiple field as columns and percentages with Chi-Square on your Microsoft Access data with Total Access Statistics
Enter frequencies that are non-negative whole numbers in each of the four cells. Do not try to enter totals; totals are automatically calculated.. Use Fisher exact test when cell frequencies in a 2 x 2 table are small, so chi-square approximation is not suitable. ...
I have always learned that if you have a contingency table that violates the chi square assumption of more than 20% of cells having expected count less...
Adequacy of the model In order to assess the adequacy of the Poisson regression model you should first look at the basic descriptive statistics for the event count data. If the count mean and variance are very different (equivalent in a Poisson distribution) then the model is likely to be over-dispersed.. The model analysis option gives a scale parameter (sp) as a measure of over-dispersion; this is equal to the Pearson chi-square statistic divided by the number of observations minus the number of parameters (covariates and intercept). The variances of the coefficients can be adjusted by multiplying by sp. The goodness of fit test statistics and residuals can be adjusted by dividing by sp. Using a quasi-likelihood approach sp could be integrated with the regression, but this would assume a known fixed value for sp, which is seldom the case. A better approach to over-dispersed Poisson models is to use a parametric alternative model, the negative binomial.. The deviance (likelihood ratio) test ...
Theory and lecture notes of Chi-square goodness-of-fit test all along with the key concepts of chi-square goodness-of-fit test, Interpreting the Claim. Tutorsglobe offers homework help, assignment help and tutors assistance on Chi-square goodness-of-fit test.
Menu location: Analysis_Exact_Fisher.. Like the chi-square test for fourfold (2 by 2) tables, Fishers exact test examines the relationship between the two dimensions of the table (classification into rows vs. classification into columns). The null hypothesis is that these two classifications are not different.. The P values in this test are computed by considering all possible tables that could give the row and column totals observed. A mathematical short cut relates these permutations to factorials; a form shown in many textbooks. StatsDirect uses the hypergeometric distribution for the calculation (Conover 1999). The test statistic that is hypergeometrically distributed is the expected value of the first count A.. This exact treatment of the fourfold table should be used instead of the chi-square test when any expected frequency is less than 1 or 20% of expected frequencies are less than or equal to 5. With StatsDirect, it is reasonable to use Fishers exact test by default because the ...
Before you begin to write, you should objectively analyze the data collected by the whole course (combined 5 lab sections). You learned from the phenotype of the heterozygous male progeny (from the cross between N2 wild type males and the Dpy Unc hermaphrodites) which strain has the x-linked mutation. Do the data from the scoring, support that conclusion that the mutations are unlinked in this strain? Note that the expected 9:3:3:1 ratio of F2 progeny of the dihybrid selfing in this strain isnt perfect. Does that mean that the two genes responsible for the two phenotypic defects arent really on different chromosomes? Do these data better support linkage? You could do a statistical test for goodness of fit (such as a Chi square) to see if it is likely that the differences between what we observed and what we expected are due to chance and, if so, that we can accept our conclusion with more confidence. Unfortunately, the Chi square test is used with a specific kind of cross that we didnt do, so ...
A total of 225 patients will be included in each group, in total 450 patients. This is based on the following: We expect a MACE rate of 2% in the group of dilatation of side branch through main vessel stent and of 8% in the group without side branch dilatation through main vessel stent. With an alfa of 5% and a strength of 80%, 206 patients will be needed in each group (two-sided chi square test) to demonstrate this difference. By including 225 patients in each group, a possible dropout before follow-up is counted for ...
An introduction to probability and statistics including methods of summarizing and describing data, basics of probability, distribution of random variables and probability distributions including the normal curve, inferential statistics including hypothesis testing and decision making, linear regression and correlation. Additional topics may include chi-square analysis and analysis of variance. Prerequisite: 105, or high school algebra I and II and geometry or equivalent. 3 credits. (QR) ...
The Royal Free Hospital has a leading vascular studies department. Read about our vascular ultrasound examinations led by clinical vascular scientists.
10. Asparouhov, T. and Muthen, B. (2006). Robust Chi Square Difference Testing with Mean and Variance Adjusted Test Statistics. Mplus Web Notes: No. 10. May 26, 2006. Contact the second author. Download this web note or the corresponding set of examples. The set of examples includes a DOS batch file called ALL.BAT which executes Step 2 and Step 3 for each data set created in Step 1. The DOS batch file uses a utility called Extractor to extract the p-value for the Chi-Square Test for Difference Testing from the H0 analysis in Step 3. The p-values are extracted and placed into the file pval.txt. The data sets created in Step 1 are not included ...
Chi-square tests are great to show if distributions differ or if two variables interact in producing outcomes. What are some examples of variables
Food insecurity is defined as a lack of consistent access to enough food for an active, healthy life. In Nevada, an estimated 80,000 individuals, aged 60 years or older, were food insecure in 2016. The primary aim of this study was to identify factors that are associated with food insecurity in older adults, aged sixty and older, in Clark County, NV. The secondary aim of this study was to identify which factors interact with each other to explain food insecurity among individuals aged sixty and older, in Clark County, NV. A secondary data analysis was conducted using data collected by Three Square Food Bank in Las Vegas, NV. Based on chi-square statistics, logistic regression models were calculated based on the levels of influence from the Social Ecological Model. Three regression models were calculated: Intrapersonal, Interpersonal, and Community. In the Intrapersonal model (χ2 = 119.839, df = 12, n = 409, p |0.001), the statistically significant variables were ambulatory disability (p = 0.043), total
THE CHI-SQUARE GOODNESS-OF-FIT TEST The chi-square goodness-of-fit test is used to analyze probabilities of multinomial distribution trials along a single
To solve this problem, determine if there is an association between the presence or absence of a given source of pigs and the presence or absence of disease X within a lot of grow-finish pigs (Figure 1). For this purpose, we will use the epidemiologists work horse, the two-by-two contingency table. The basic approach to the statistical analysis of such a table is to first determine the probability that the distribution is due to a random process. The tests most often used for this purpose are the Chi square, the Chi square corrected for continuity, and Fishers exact test. The Chi square corrected for continuity is useful when cell values are less than 30. The Fishers exact test is used when the expected value of any one cell is less than 5. Because our contingency table has small numbers, we must use the Fishers exact test. Thus, for each origin, we make up a two-by-two table, as illustrated by Table 1 for Source 9.. ...
... use ultrasound (sound wave) technology to assess the flow of blood in arteries and veins in the arms, legs, and neck.
... use ultrasound (sound wave) technology to assess the flow of blood in arteries and veins in the arms, legs, and neck.
Descriptive and inferential statistics, including t-tests, correlation, chi square, tests of normality, and distribution-free procedures. Other topics include independent groups, repeated measures and factorail ANOVA, mulitple comparisons, multiple regression and ANCOVA. Return to Course Schedule. ...
日前,筆者於《立場新聞》發表了《無知害人害畜 相信動物傳心非但迷信且不道德》一文(後稱《無》文...
In the search of predictors of inadequate physical activity, an investigation was conducted into the association between multimorbidity and physical activity (PA). So far the sum of diseases used as a measure of multimorbidity reveals an inverse association. How specific combinations of chronic diseases are associated with PA remains unclear. The objective of this study is to identify clusters of multimorbidity that are associated with PA. Cross-sectional data of 3,386 patients from the 2003 wave of the Dutch cohort study SMILE were used. Ward’s agglomerative hierarchical clustering was executed to establish multimorbidity clusters. Chi-square statistics were used to assess the association between clusters of chronic diseases and PA, measured in compliance with the Dutch PA guideline. The highest rate of PA guideline compliance was found in patients the majority of whom suffer from liver disease, back problems, rheumatoid arthritis, osteoarthritis, and inflammatory joint disease (62.4%). The
The pattern of longitudinal changes in cholesterol levels has important implications for screening policies and for understanding the role of cholesterol as a risk factor for coronary heart disease. We explored a variety of longitudinal models to predict changes in cholesterol over several years, emphasizing the probability that an individual will develop a cholesterol level that requires further diagnostic tests or treatment. The first question was whether measured cholesterol is Markovian. A chi-square statistic based on the bootstrap and motivated by the Chapman-Kolmogorov equations established that it is not. Related bootstrap-based tests indicate that the probability structure of measured cholesterol is not that of a low order autoregressive moving average (ARMA) model. We then tested several alternative models to predict future cholesterol levels from the pattern of previous measured values, using receiver-operating characteristic (ROC) curves to summarize the sensitivity and specificity ...
The use and misuse of statistics in real life situations; basic statistical measures of central tendency and of dispersion, frequency distributions, elements of probability, binomial and normal distributions, small and large sample hypothesis testing, confidence intervals, chi square test, and regression. May not be taken by students with credit for AMS 110, 310, 311, 312; ECO 320; POL 201; PSY 201; or SOC 202. This course has been designated as a High Demand/Controlled Access (HD/CA) course. Students registering for HD/CA courses for the first time will have priority to do so.. Prerequisite: Satisfaction of entry skill in mathematics requirement (Skill 1) or satisfactory completion of D.E.C. C. 3 credits. ...
Statistical Analysis. Results are expressed as percentages for categorical variables and as median and interquartile range for continuous variables. Continuous variables were compared using the Mann-Whitney U test. Proportions were compared using the chi-square test. Statistical differences were considered when p value was < 0.05 ...
The information on deviance is also provided. We can use the residual deviance to perform a goodness of fit test for the overall model. The residual deviance is the difference between the deviance of the current model and the maximum deviance of the ideal model where the predicted values are identical to the observed. Therefore, if the residual difference is small enough, the goodness of fit test will not be significant, indicating that the model fits the data. We conclude that the model fits reasonably well because the goodness-of-fit chi-squared test is not statistically significant. If the test had been statistically significant, it would indicate that the data do not fit the model well. In that situation, we may try to determine if there are omitted predictor variables, if our linearity assumption holds and/or if there is an issue of over-dispersion ...
Vascular studies are a noninvasive procedure used to assess the blood flow in arteries and veins. A transducer is placed on the skin at certain locations a
Nous vous invitons à utiliser notre collection de fiches signalétiques des médicaments sur ordonnance, elle est activée par MediResource. - Médicaments dont la première lettre est Z
Nous vous invitons à utiliser notre collection de fiches signalétiques des médicaments sur ordonnance, elle est activée par MediResource. - Médicaments dont la première lettre est A
Typically the square of the difference is compared to a chi-squared distribution. ... Recalling that a quadratic form of normal distribution has a Chi-squared distribution: n. (. R. θ. ^. n. −. r. ). ′. [. R. V. R ... chi _{Q}^{2}}. Rearranging n finally gives: (. R. θ. ^. n. −. r. ). ′. [. R. (. V. /. n. ). R. ′. ]. −. 1. (. R. θ. ^. n. −. r ... multiplying by R has distribution: R. n. (. θ. ^. n. −. θ. ). =. n. (. R. θ. ^. n. −. r. ). →. D. N. (. 0. ,. R. V. R. ′. ). {\ ...
has a chi square distribution with n − 1 degrees of freedom and thus its square root, n. −. 1. s. /. σ. {\displaystyle {\sqrt { ... where the correction factor c4(n) is the scale mean of the chi distribution with n − 1 degrees of freedom, μ. 1. (. n. −. 1. ) ... has a chi distribution with n − 1 degrees of freedom. Consequently, calculating the expectation of this last expression and ... Other distributions[edit]. In cases where statistically independent data are modelled by a parametric family of distributions ...
"On limiting distribution laws of statistics analogous to pearson's chi-square". Statistics: A Journal of Theoretical and ... Z. W. Birnbaum; I. Vincze (1973). "Limiting Distributions of Statistics Similar to Student's". Annals of Statistics. 1 (1973): ... Vincze, István (1996). "Cramér-Rao type inequality and a problem of mixture of distributions". Mathematical Institute, Slovak ... empirical distribution, Cramér-Rao inequality, and information theory. Considered by many, as an expert in theoretical and ...
This test yields a Wald statistic which follows a chi-square distribution. In this case the null hypothesis being tested is H0 ... G2 approximately follows a chi square distribution, especially with larger samples. Therefore, it is evaluated by the degrees ... Determination of DIF is made by evaluating the obtained chi-square statistic with 2 degrees of freedom. Additionally, parameter ... In this case, the absence of DIF is determined by the fact that the conditional probability distribution of Y is not dependent ...
"A note on the distribution of the sum of chi-squares", Sankhya, 7 (1945), 27 - 28. "On some analogues of the amount of ... Distance between statistical distributions had been addressed in 1936 by Bhattacharyya's mentor, Mahalanobis, who proposed the ... Inst., 33, Part II (1951). "On some uses of the t-distribution in multivariate analysis", Sankhya, 12 (1952), 89 - 104. "Notes ... "On a measure of divergence between two statistical populations defined by their probability distributions", Bull. Cal. Math. ...
Curran, P. J., Bollen, K. A., Paxton, P., Kirby, J., & Chen, F. (2002). The noncentral chi-square distribution in misspecified ...
... chi-square distribution with zero degrees of freedom concentrates all probability at zero. All of this leaves open the question ... The chi-squared distribution with n degrees of freedom is the probability distribution of the sum X 1 2 + ⋯ + X n 2 {\ ... The noncentral chi-squared distribution with zero degrees of freedom and with noncentrality parameter μ is the distribution of ... then the sum of squares above has a non-central chi-squared distribution with n degrees of freedom and "noncentrality parameter ...
The residual sum-of-squares ‖. y. −. H. y. ‖. 2. {\displaystyle \,y-Hy\,^{2}}. has a generalized chi-squared distribution, and ... then the residual sum of squares has a scaled chi-squared distribution (scaled by the factor σ. 2. {\displaystyle \sigma ^{2}} ... the sums-of-squares no longer have scaled chi-squared distributions. Comparison of sum-of-squares with degrees-of-freedom is no ... In the example above, the residual sum-of-squares is ∑. i. =. 1. n. (. X. i. −. X. ¯. ). 2. =. ‖. X. 1. −. X. ¯. ⋮. X. n. −. X ...
Chi-square test, and T-Test. The program was offered in both disk and cassette stand-alone versions, as well as in a compendium ... Calculations performed by the program included mean, variance, standard deviation, Pearson correlation, normal distribution, ...
... chi ^{2}=wy^{2}\;\left[=193>\chi ^{2}(p=0.001,\;df=1)=10.8\right]} follows the chi-square distribution with d f = 1 {\ ... chi ^{2}} test calculating χ 2 = ( a d − b c ) 2 N A B C D ( = 336 , for data in Table 3; P < 0.001 ) {\displaystyle \chi ^{2 ...
Sawilowsky, S. (1985). "A comparison of random normal scores test under the F and Chi-square distributions to the 2x2x2 ANOVA ... Treat the mean for each group as a score, and compute the variability (again, the sum of squares) of those three scores. When ... Under the truth of the null hypothesis, the sampling distribution of the F ratio depends on the degrees of freedom for the ... or sum of squares) of scores on some dependent variable will be the same within each group. When divided by the degrees of ...
Pinheiro and Bates showed in 2000 that the true distribution of this likelihood ratio chi-square statistic could be ... the asymptotic distribution for the test will be χ. 2. (. 1. ). {\displaystyle \chi ^{2}(1)}. , the χ. 2. {\displaystyle \chi ... displaystyle \chi ^{2}(k)}. and χ. 2. (. k. −. 1. ). {\displaystyle \chi ^{2}(k-1)}. . (With k = 1, χ. 2. (. 0. ). {\ ... displaystyle \chi ^{2}(3)}. and χ. 2. (. 4. ). {\displaystyle \chi ^{2}(4)}. was a good match for actual p-values obtained by ...
Royen worked mainly on probability distributions, in particular multivariate chi-squares and gamma distributions, to improve ... Thomas Royen: A simple proof of the Gaussian correlation conjecture extended to some multivariate gamma distributions, in: ... supplemented by Thomas Royen: Some probability inequalities for multivariate gamma and normal distributions, in: arXiv.org, 2. ... Royen, Thomas (2015-07-02). "Some probability inequalities for multivariate gamma and normal distributions". arXiv:1507.00528 [ ...
... the sums-of-squares no longer have scaled chi-squared distributions. Comparison of sum-of-squares with degrees-of-freedom is no ... The residual sum-of-squares ‖ y − H y ‖ 2 {\displaystyle \,y-Hy\,^{2}} has a generalized chi-squared distribution, and the ... the sums of squares have scaled chi-squared distributions, with the corresponding degrees of freedom. The F-test statistic is ... these sums-of-squares no longer have (scaled, non-central) chi-squared distributions, and dimensionally defined degrees-of- ...
This result is used to justify using a normal distribution, or a chi square distribution (depending on how the test statistic ... This might not be true even if the error term is assumed to be drawn from identical distributions. For example, the error term ... When using some statistical techniques, such as ordinary least squares (OLS), a number of assumptions are typically made. One ... In 1980, White proposed a consistent estimator for the variance-covariance matrix of the asymptotic distribution of the OLS ...
... the objective function is a random variable which follows a chi-square distribution, since it is the sum of the square of ... one only has to compare the value of the objective function with the critical value of the chi square distribution. The ... of the probability density function of a chi-square distribution (e.g. the 95th percentile for a 95% confidence) gives an ... The chi square test gives only a rough indication about the existence of gross errors, and it is easy to conduct: ...
The Wald test can be evaluated against a chi-square distribution.. References[edit]. *^ a b Pearson, Karl (1900). "On the ... Other examples of chi-squared tests[edit]. One test statistic that follows a chi-squared distribution exactly is the test that ... Using the chi-squared distribution to interpret Pearson's chi-squared statistic requires one to assume that the discrete ... Without other qualification, 'chi-squared test' often is used as short for Pearson's chi-squared test. The chi-squared test is ...
... an approach based on the chi-square distribution for combining the individual word probabilities into a combined probability ( ... Robinson's method used math-intensive algorithms combined with Chi-square statistical testing to enable computers to examine an ... Fischer's combination of probabilities into a chi-squared distribution, has been extensively tested and is used by the most ... Gary Robinson's Linux Journal article discussed using the chi squared distribution. Ben Kamens, Fog Creek Publishing, Bayesian ...
... specifies a chi-squared distribution which describes the associated sum of squares, while the same is true for "treatments" if ... Using the F-distribution is a natural candidate because the test statistic is the ratio of two scaled sums of squares each of ... which follows a scaled chi-squared distribution. The expected value of F is 1. +. n. σ. Treatment. 2. /. σ. Error. 2. {\ ... to the F-distribution with I. −. 1. {\displaystyle I-1}. , n. T. −. I. {\displaystyle n_{T}-I}. degrees of freedom. ...
... From Wikipedia, the free encyclopedia. (Redirected from Noncentral chi-square distribution ... Various chi and chi-squared distributions Name. Statistic chi-squared distribution. ∑. 1. k. (. X. i. −. μ. i. σ. i. ). 2. {\ ... displaystyle \chi ^{2}}. distribution is a generalization of the chi-squared distribution. This distribution often arises in ... Related distributions[edit]. *If V. {\displaystyle V}. is chi-squared distributed V. ∼. χ. k. 2. {\displaystyle V\sim \chi _{k ...
Usability of these transformations may be hampered by the need to take the square roots of negative numbers. ... Various chi and chi-squared distributions. Name. Statistic. chi-squared distribution. ∑. 1. k. (. X. i. −. μ. i. σ. i. ). 2. {\ ... displaystyle \chi ^{2}}. distribution is a generalization of the chi-squared distribution. This distribution often arises in ... Related distributions[edit]. *If V. {\displaystyle V}. is chi-squared distributed V. ∼. χ. k. 2. {\displaystyle V\sim \chi _{k ...
... size reduction after compression chi square distribution test: 40% < deviation < 60% mean value test: 127.4x / 127.5 Monte ...
... chi-squared test, a statistical procedure whose results are evaluated by reference to the chi-square distribution ...
... the Pearson's chi-square test will give accurate results. For small samples, the chi-square reference distribution cannot be ... of the jackknife variance to the sample variance tends to be distributed as one half the square of a chi square distribution ... where the rate of convergence of the estimator is not the square root of the sample size or when the limiting distribution is ... Permutation tests exist for any test statistic, regardless of whether or not its distribution is known. Thus one is always free ...
... that has an approximate chi-square distribution when the sample size is large: X 2 = 2 ∑ O i j ln ⁡ O i j E i j , {\ ... If the chi-square difference is smaller than the chi-square critical value, the new model fits the data significantly better ... The chi-square difference test is computed by subtracting the likelihood ratio chi-square statistics for the two models being ... To conduct chi-square analyses, one needs to break the model down into a 2 × 2 or 2 × 1 contingency table. For example, if one ...
... the square root of) a central moment. ... Probability distribution. *Sampling distribution *Order ...
In this paper, a simple chi-square approximation for the cumulative distribution of the F-distribution is obtained via an ... For example, it is used for testing: equality of variances of two independent normal distributions, equality of means in the ... This new approximation exhibits remarkable accuracy even when the degrees of freedom of the F distribution are small. ... F distribution is one of the most frequently used distributions in statistics. ...
Table 5 Chi-Square Probability Distribution Selected right-tail areas - Selection from The Complete Idiots Guide to Statistics ... Chi-Square Probability Distribution Table 5 provides the chi-square for the corresponding value of alpha and the number of ... Chi-Square Probability Distribution. Table 5 provides the chi-square for the corresponding value of alpha and the number of ...
A Powerful Variant-Set Association Test Based on Chi-Square Distribution Message Subject (Your Name) has forwarded a page to ... A Powerful Variant-Set Association Test Based on Chi-Square Distribution. Zhongxue Chen, Tong Lin and Kai Wang ... A Powerful Variant-Set Association Test Based on Chi-Square Distribution. Zhongxue Chen, Tong Lin and Kai Wang ... A Powerful Variant-Set Association Test Based on Chi-Square Distribution. Zhongxue Chen, Tong Lin and Kai Wang ...
We derive Laguerre expansions for the density and distribution functions of a sum of positive weighted noncentral chi-square ... Ashour, S. K. andAbdel-Samad, A. I. (1990). On the computation of noncentral chi-square distribution function.Communications in ... Gideon, R. A. andGurland, J. (1977). Some alternative expansions for the distribution function of a noncentral chi-square ... We derive Laguerre expansions for the density and distribution functions of a sum of positive weighted noncentral chi-square ...
Students compare the chi-square distribution to the standard normal distribution and determine how the Chi-Square distribution ... Students compare the chi-square distribution to the standard normal distribution and determine how the Chi-Square distribution ... Problem 2 gives students the opportunity to explore the critical values for a Chi-Square Distribution. They find the critical ... In Problem 1, students will explore the characteristics of the Chi-Square Distribution. They will increase the degree of ...
Chi-square distribution a distribution in which a variable is distributed like the sum of the the squares of any given ... The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of ... Retrieved from "https://www.biology-online.org/dictionary/index.php?title=Chi-square_distribution&oldid=57790" ... independent random variable, each of which has a normal distribution with mean of zero and variance of one. ...
What is Chi-square distribution? Meaning of Chi-square distribution as a legal term. What does Chi-square distribution mean in ... Definition of Chi-square distribution in the Legal Dictionary - by Free online English dictionary and encyclopedia. ... Chi-square distribution legal definition of Chi-square distribution https://legal-dictionary.thefreedictionary.com/Chi-square+ ... 1] has a noncentral chi-square distribution then the distribution of X = [square root of [X. ...
Distribution for random variables constrained to be equal to or greater than 0 and which (unlike normal distribution) traces an ... Distribution for random variables constrained to be equal to or greater than 0 and which (unlike normal distribution) traces an ...
Chi-Square Distribution Female Glucose Tolerance Test Humans Incidence Male Middle Aged Multivariate Analysis Myocardial ... Chi-Square Distribution Cross-Sectional Studies Female Humans Linear Models Longitudinal Studies Middle Aged Mouth, Edentulous ... Chi-Square Distribution Confounding Factors (Epidemiology) Finland Humans Longitudinal Studies Male Manuals as Topic Middle ... Chi-Square Distribution Cohort Studies Female Finland Follow-Up Studies Humans Male Mandibular Condyle - physiopathology - ...
Standard Normal Distribution. Remarks:. The Chi-Square distribution is based on a sum of squares, therefore the value of X^2 ... The Chi-square distribution, is derived from the > Normal distribution. It is the distribution of a sum of squared Normal ... The Chi-square distribution. Example:. Prob( X^2 >= , Degrees of Freedom=. ) <= X^2 = >. Degrees of Freedom = >. ... The importance of the Chi-square distribution stems from the fact that it describes the distribution of the Variance of a ...
F and Chi square distributions. Click the image or link below for tables of critical test values for different distributions. ...
... distribution from CHEM 115L at Grand Canyon. Chi square test 2-The student population at the state college consists of 55% ... Chi-square+Test-Gender+distribution - Chi square test 2-The.... This preview shows document pages 1 - 2. Sign up to view the ... Chi square test 2-The student population at the state college consists of 55% female and 45% males. a- The college theater ... Is the gender distribution for theater goers significantly different from the distribution for the general college? Test at the ...
Can we use chi-square distribution and central limit theorem to find the approximate normal distribution? ... Okay, so I am interested if there is a way to derive the variance for a Chi-Square distribution using the property that it is ... Note: I can solve this using integration of the PDF for the Chi-Square distribution, but I was wondering if there is any way to ... Variance of Chi Square Distribution as the Sum of Unit Normal Random Variables. Ask Question ...
Actually, when the null hypothesis is not trivially violated, the noncentral chi-square distribution cannot describe the LR ... noncentral chi-square distribution is commonly used to describe the behavior of the likelihood ratio (LR) statistic under ... it is widely believed that the noncentral chi-square distribution is justified by statistical theory. ... Due to the inaccessibility of the rather technical literature for the distribution of the LR statistic, ...
Tags chi sq test chi square chi square help what test distribution dot product six sigma weighted average ... I think I need to steer towards some sort of Chi-Square Distribution. I also think I need some bounding built in to take care ... Should I use some sort of Chi Square Distribution or another method... Any assistance is greatly appreciated.. ...
... The chi-square ( ) distribution is obtained from the values of the ratio of the sample variance and ... Chi-Square Probabilities. Since the chi-square distribution isnt symmetric, the method for looking up left-tail values is ... Properties of the Chi-Square. *Chi-square is non-negative. Is the ratio of two non-negative values, therefore must be non- ... There are many different chi-square distributions, one for each degree of freedom. ...
Chi-square distribution come together and discuss about Chi-square distribution. Please use the message board below to post ... F-distribution Forum. • Chi distribution Forum. • Exponential distribution Forum. • Erlang distribution Forum. • Linear ... Standard normal distribution Forum. • Iid Forum. • Noncentral chi-square distribution Forum. • Idempotent matrix Forum. • Rank ... There are no entries in Chi-square distribution forum. Become the first person to post messages in this forum by using the form ...
Class: Chi-square distribution. http://cll.niimm.ksu.ru/ontologies/mathematics#E2533. Annotations (3). * comment "В.С. ...
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CHI-SQUARE DISTRIBUTION FUNCTION - Selection from Introduction to Probability and Stochastic Processes with Applications [Book] ... APPENDIX D STATISTICAL TABLES D.1 BINOMIAL PROBABILITIES D.2 POISSON PROBABILITIES D.3 STANDARD NORMAL DISTRIBUTION FUNCTION D. ... D.3 STANDARD NORMAL DISTRIBUTION FUNCTION. D.4 CHI-SQUARE DISTRIBUTION FUNCTION. ...
Chi-square distribution The chi-square distribution has one parameter k, the degrees of freedom. The chi squared distribution ... Chi square. chi square test, chi square distribution, expected frequency, observed frequency. contingency table, significance ... Chi-square test explained. Chi-square test is based on the chi square distribution. It is used for the goodness-of-fit test ... chi square is greater than the critical value of chi square that cuts off the upper 5% of the distribution at our particular ...
Upper limit of integration of the non-central chi-square distribution. Input range: [0, +infinity). Search range: [0,1E300] ... Degrees of freedom of the non-central chi-square distribution. Input range: (0, +infinity). Search range: [ 1E-300, 1E300] ... The integral from 0 to X of the non-central chi-square distribution. Input range: [0, 1-1E-16). ... Non-centrality parameter of the non-central chi-square distribution. Input range: [0, +infinity). Search range: [0,1E4] ...
cdfchi - cumulative distribution function chi-square distribution. *cdff - cumulative distribution function Fisher distribution ... cdfnor - cumulative distribution function normal distribution. *cdfpoi - cumulative distribution function poisson distribution ... Upper limit of integration of the non-central chi-square distribution. Input range: [0, +infinity). Search range: [0,1E300] ... Degrees of freedom of the non-central chi-square distribution. Input range: (0, +infinity). Search range: [ 1E-300, 1E300] ...
Chi-Square Distribution. The chi-square distribution is a univariate distribution which results when univariate-normal ... chi-square distribution *Wishart distribution Normal Distribution. The normal, or Gaussian, distribution is one of the most ... These chi-square distributions are themselves additive. That is, a chi-square-distributed variable with d1 degrees of freedom ... the chi-square distribution is skewed to the right, and has a minimum of 0. The degrees of freedom of the resulting chi-square ...
... for the parameters of a normal distribution, using the sample data in the vector data. ... Add a scale parameter to the chi-square distribution for adapting to the scale of data and fit it. First, generate sample data ... Estimate the parameters of the noncentral chi-square distribution from the sample data. To do this, custom define the ... Generate sample data of size 1000 from a noncentral chi-square distribution with degrees of freedom 8 and noncentrality ...
  • The method of least squares had been introduced into geodesy by Gauss and Helmert wrote a fine book on least squares (1872, with a second edition in 1907) in this tradition, which became a standard text. (wikipedia.org)
  • Data were analyzed using paired Wilcoxon signed-rank tests, Spearman rank correlation coefficients, and Fischer's exact chi-square tests (alpha = 0.05) where appropriate. (nih.gov)