Adverse or favorable selection bias exhibited by insurers or enrollees resulting in disproportionate enrollment of certain groups of people.

The introduction of error due to systematic differences in the characteristics between those selected and those not selected for a given study. In sampling bias, error is the result of failure to ensure that all members of the reference population have a known chance of selection in the sample.

Insurance providing coverage of medical, surgical, or hospital care in general or for which there is no specific heading.

The anterior portion of the head that includes the skin, muscles, and structures of the forehead, eyes, nose, mouth, cheeks, and jaw.

Generally refers to the amount of protection available and the kind of loss which would be paid for under an insurance contract with an insurer. (Slee & Slee, Health Care Terms, 2d ed)

Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions.

The complex of political institutions, laws, and customs through which the function of governing is carried out in a specific political unit.

Differential and non-random reproduction of different genotypes, operating to alter the gene frequencies within a population.

Coverage by contract whereby one part indemnifies or guarantees another against loss by a specified contingency.

Health insurance to provide full or partial coverage for long-term home care services or for long-term nursing care provided in a residential facility such as a nursing home.

Insurance providing for payment of a stipulated sum to a designated beneficiary upon death of the insured.

Organizations which assume the financial responsibility for the risks of policyholders.

Federal, state, or local government organized methods of financial assistance.

An organization of insurers or reinsurers through which particular types of risk are shared or pooled. The risk of high loss by a particular insurance company is transferred to the group as a whole (the insurance pool) with premiums, losses, and expenses shared in agreed amounts.

The term "United States" in a medical context often refers to the country where a patient or study participant resides, and is not a medical term per se, but relevant for epidemiological studies, healthcare policies, and understanding differences in disease prevalence, treatment patterns, and health outcomes across various geographic locations.

Individuals or groups with no or inadequate health insurance coverage. Those falling into this category usually comprise three primary groups: the medically indigent (MEDICAL INDIGENCY); those whose clinical condition makes them medically uninsurable; and the working uninsured.

The level of governmental organization and function at the national or country-wide level.

Criteria and standards used for the determination of the appropriateness of the inclusion of patients with specific conditions in proposed treatment plans and the criteria used for the inclusion of subjects in various clinical trials and other research protocols.

Payments or services provided under stated circumstances under the terms of an insurance policy. In prepayment programs, benefits are the services the programs will provide at defined locations and to the extent needed.

Insurance providing coverage for dental care.

Smallest political subdivisions within a country at which general governmental functions are carried-out.

Payment by a third-party payer in a sum equal to the amount expended by a health care provider or facility for health services rendered to an insured or program beneficiary. (From Facts on File Dictionary of Health Care Management, 1988)

Health insurance plans for employees, and generally including their dependents, usually on a cost-sharing basis with the employer paying a percentage of the premium.

Innovation and improvement of the health care system by reappraisal, amendment of services, and removal of faults and abuses in providing and distributing health services to patients. It includes a re-alignment of health services and health insurance to maximum demographic elements (the unemployed, indigent, uninsured, elderly, inner cities, rural areas) with reference to coverage, hospitalization, pricing and cost containment, insurers' and employers' costs, pre-existing medical conditions, prescribed drugs, equipment, and services.

Components of a national health care system which administer specific services, e.g., national health insurance.

A plan for collecting and utilizing data so that desired information can be obtained with sufficient precision or so that an hypothesis can be tested properly.

Health insurance coverage for all persons in a state or country, rather than for some subset of the population. It may extend to the unemployed as well as to the employed; to aliens as well as to citizens; for pre-existing conditions as well as for current illnesses; for mental as well as for physical conditions.

Exercise of governmental authority to control conduct.

That distinct portion of the institutional, industrial, or economic structure of a country that is controlled or owned by non-governmental, private interests.

Insurance against loss resulting from liability for injury or damage to the persons or property of others.

The degree to which individuals are inhibited or facilitated in their ability to gain entry to and to receive care and services from the health care system. Factors influencing this ability include geographic, architectural, transportational, and financial considerations, among others.

The design, completion, and filing of forms with the insurer.

National Health Insurance in the United States refers to a proposed system of healthcare financing that would provide comprehensive coverage for all residents, funded through a combination of government funding and mandatory contributions, and administered by a public agency.

Social and economic factors that characterize the individual or group within the social structure.

Insurance providing a broad range of medical services and supplies, when prescribed by a physician, whether or not the patient is hospitalized. It frequently is an extension of a basic policy and benefits will not begin until the basic policy is exhausted.

Insurance providing coverage for physical injury suffered as a result of unavoidable circumstances.

Administrative units of government responsible for policy making and management of governmental activities.

Phenomenon of workers' usually exhibiting overall death rates lower than those of the general population due to the fact that the severely ill and disabled are ordinarily excluded from employment.

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.

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.

The amounts spent by individuals, groups, nations, or private or public organizations for total health care and/or its various components. These amounts may or may not be equivalent to the actual costs (HEALTH CARE COSTS) and may or may not be shared among the patient, insurers, and/or employers.

Federal program, created by Public Law 89-97, Title XIX, a 1965 amendment to the Social Security Act, administered by the states, that provides health care benefits to indigent and medically indigent persons.

The level of governmental organization and function below that of the national or country-wide government.

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.

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.

Decisions, usually developed by government policymakers, for determining present and future objectives pertaining to the health care system.

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.

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.

Programs and activities sponsored or administered by local, state, or national governments.

The form and structure of analytic studies in epidemiologic and clinical research.

Elements of limited time intervals, contributing to particular results or situations.

Health insurance providing benefits to cover or partly cover hospital expenses.

Conditional probability of exposure to a treatment given observed covariates.

Public Law 104-91 enacted in 1996, was designed to improve the efficiency and effectiveness of the healthcare system, protect health insurance coverage for workers and their families, and to protect individual personal health information.

State plans prepared by the State Health Planning and Development Agencies which are made up from plans submitted by the Health Systems Agencies and subject to review and revision by the Statewide Health Coordinating Council.

The influence of study results on the chances of publication and the tendency of investigators, reviewers, and editors to submit or accept manuscripts for publication based on the direction or strength of the study findings. Publication bias has an impact on the interpretation of clinical trials and meta-analyses. Bias can be minimized by insistence by editors on high-quality research, thorough literature reviews, acknowledgement of conflicts of interest, modification of peer review practices, etc.

Factors that can cause or prevent the outcome of interest, are not intermediate variables, and are not associated with the factor(s) under investigation. They give rise to situations in which the effects of two processes are not separated, or the contribution of causal factors cannot be separated, or the measure of the effect of exposure or risk is distorted because of its association with other factors influencing the outcome of the study.

The integration of epidemiologic, sociological, economic, and other analytic sciences in the study of health services. Health services research is usually concerned with relationships between need, demand, supply, use, and outcome of health services. The aim of the research is evaluation, particularly in terms of structure, process, output, and outcome. (From Last, Dictionary of Epidemiology, 2d ed)