###### displaystyle

- mu ,\sigma ^{2})={\frac {1}{\sqrt {2\pi \sigma ^{2}}}}\;e^{-{\frac {(x-\mu )^{2}}{2\sigma ^{2}}}}} where μ {\displaystyle \mu } is the mean or expectation of the distribution (and also its median and mode). (wikipedia.org)
- σ {\displaystyle \sigma } is the standard deviation σ 2 {\displaystyle \sigma ^{2}} is the variance The simplest case of a normal distribution is known as the standard normal distribution. (wikipedia.org)
- The factor 1 / 2 {\displaystyle 1/2} in the exponent ensures that the distribution has unit variance (and therefore also unit standard deviation). (wikipedia.org)
- 0 {\displaystyle \sigma >0} , has the following properties: It is symmetric around the point x = μ {\displaystyle x=\mu } , which is at the same time the mode, the median and the mean of the distribution. (wikipedia.org)
- The mode of the distribution is the value of x {\displaystyle x} for which the density is maximised. (wikipedia.org)
- Half-t distribution Half-Normal Distribution at MathWorld (note that MathWorld uses the parameter θ = 1 σ π / 2 {\displaystyle \theta ={\frac {1}{\sigma }}{\sqrt {\pi /2}}} ) Leone, F. C. (wikipedia.org)
- Then we say that the complex random vector Z = X + i Y {\displaystyle Z=X+iY\,} has the complex normal distribution. (wikipedia.org)
- The generalized normal log-likelihood function has infinitely many continuous derivates (i.e. it belongs to the class C∞ of smooth functions) only if β {\displaystyle \textstyle \beta } is a positive, even integer. (wikipedia.org)
- Then the probability density function (pdf) of the skew-normal distribution with parameter α {\displaystyle \alpha } is given by f ( x ) = 2 ϕ ( x ) Φ ( α x ) . {\displaystyle f(x)=2\phi (x)\Phi (\alpha x). (wikipedia.org)
- One can verify that the normal distribution is recovered when α = 0 {\displaystyle \alpha =0} , and that the absolute value of the skewness increases as the absolute value of α {\displaystyle \alpha } increases. (wikipedia.org)
- they can be seen as the result of applying the matrix A to a collection of independent Gaussian variables Z. The multivariate normal distribution is said to be "non-degenerate" when the symmetric covariance matrix Σ {\displaystyle {\boldsymbol {\Sigma }}} is positive definite. (wikipedia.org)
- The equation above reduces to that of the univariate normal distribution if Σ {\displaystyle {\boldsymbol {\Sigma }}} is a 1 × 1 {\displaystyle 1\times 1} matrix (i.e. a single real number). (wikipedia.org)
- e^{-\sigma ^{2}/2}} The circular standard deviation, which is a useful measure of dispersion for the wrapped normal distribution and its close relative, the von Mises distribution is given by: s = ln ( R − 2 ) 1 / 2 = σ {\displaystyle s=\ln(R^{-2})^{1/2}=\sigma } A series of N measurements zn = e iθn drawn from a wrapped normal distribution may be used to estimate certain parameters of the distribution. (wikipedia.org)
- Given a log-normally distributed random variable X {\displaystyle X} and two parameters μ {\displaystyle \mu } and σ {\displaystyle \sigma } that are, respectively, the mean and standard deviation of the variable's natural logarithm, then the logarithm of X {\displaystyle X} is normally distributed, and we can write X {\displaystyle X} as X = e μ + σ Z {\displaystyle X=e^{\mu +\sigma Z}} with Z {\displaystyle Z} a standard normal variable. (wikipedia.org)
- Let Φ {\displaystyle \Phi } and φ {\displaystyle \varphi } be respectively the cumulative probability distribution function and the probability density function of the N(0,1) distribution. (wikipedia.org)
- end{aligned}}} The cumulative distribution function is F X ( x ) = Φ ( ( ln x ) − μ σ ) {\displaystyle F_{X}(x)=\Phi \left({\frac {(\ln x)-\mu }{\sigma }}\right)} where Φ {\displaystyle \Phi } is the cumulative distribution function of the standard normal distribution (i.e. (wikipedia.org)
- All moments of the log-normal distribution exist and E [ X n ] = e n μ + n 2 σ 2 / 2 {\displaystyle \operatorname {E} [X^{n}]=e^{n\mu +n^{2}\sigma ^{2}/2}} This can be derived by letting z = ln ( x ) − ( μ + n σ 2 ) σ {\displaystyle z={\frac {\ln(x)-(\mu +n\sigma ^{2})}{\sigma }}} within the integral. (wikipedia.org)
- mu ,\lambda ,\alpha ,\beta )={\frac {\beta ^{\alpha }{\sqrt {\lambda }}}{\Gamma (\alpha ){\sqrt {2\pi }}}}\,\tau ^{\alpha -{\frac {1}{2}}}\,e^{-\beta \tau }\,e^{-{\frac {\lambda \tau (x-\mu )^{2}}{2}}}} By construction, the marginal distribution over τ {\displaystyle \tau } is a gamma distribution, and the conditional distribution over x {\displaystyle x} given τ {\displaystyle \tau } is a Gaussian distribution. (wikipedia.org)
- x_{n}\}} , the posterior distribution of μ {\displaystyle \mu } and τ {\displaystyle \tau } given this dataset can be analytically determined by Bayes' theorem. (wikipedia.org)
- mathbf {W} ,\nu )} By construction, the marginal distribution over Λ {\displaystyle {\boldsymbol {\Lambda }}} is a Wishart distribution, and the conditional distribution over μ {\displaystyle {\boldsymbol {\mu }}} given Λ {\displaystyle {\boldsymbol {\Lambda }}} is a multivariate normal distribution. (wikipedia.org)
- The marginal distribution over μ {\displaystyle {\boldsymbol {\mu }}} is a multivariate t-distribution. (wikipedia.org)
- The distribution has heavy tails and a sharp peak at μ {\displaystyle \mu } and, because of this, it has applications in variable selection. (wikipedia.org)
- while α λ β ( x − μ ) {\displaystyle {\sqrt {\frac {\alpha \lambda }{\beta }}}(x-\mu )} follows a t distribution with 2 α {\displaystyle 2\alpha } degrees of freedom. (wikipedia.org)
- Generation of random variates is straightforward: Sample Σ {\displaystyle {\boldsymbol {\Sigma }}} from an inverse Wishart distribution with parameters Ψ {\displaystyle {\boldsymbol {\Psi }}} and ν {\displaystyle \nu } Sample μ {\displaystyle {\boldsymbol {\mu }}} from a multivariate normal distribution with mean μ 0 {\displaystyle {\boldsymbol {\mu }}_{0}} and variance 1 λ Σ {\displaystyle {\boldsymbol {\tfrac {1}{\lambda }}}{\boldsymbol {\Sigma }}} The normal-Wishart distribution is essentially the same distribution parameterized by precision rather than variance. (wikipedia.org)
- The process X ( t ) {\displaystyle X(t)} at time 1 has the normal-inverse Gaussian distribution described above. (wikipedia.org)

###### Gaussian

- The normal (or Gaussian) distribution is one of the most commonly observed and is the starting point for modeling many natural processes. (uky.edu)
- In probability theory, the normal (or Gaussian) distribution is a very common continuous probability distribution. (wikipedia.org)
- A random variable with a Gaussian distribution is said to be normally distributed and is called a normal deviate. (wikipedia.org)
- There are also theoretical distributions, of which the best known is the normal distribution (sometimes called the Gaussian distribution), which is shown in figure 2. (bmj.com)
- The generalized normal distribution or generalized Gaussian distribution (GGD) is either of two families of parametric continuous probability distributions on the real line. (wikipedia.org)
- In probability theory and statistics, the multivariate normal distribution or multivariate Gaussian distribution is a generalization of the one-dimensional (univariate) normal distribution to higher dimensions. (wikipedia.org)
- In probability theory and statistics, the normal-gamma distribution (or Gaussian-gamma distribution) is a bivariate four-parameter family of continuous probability distributions. (wikipedia.org)
- The normal-inverse Gaussian distribution (NIG) is a continuous probability distribution that is defined as the normal variance-mean mixture where the mixing density is the inverse Gaussian distribution. (wikipedia.org)
- The parameters of the normal-inverse Gaussian distribution are often used to construct a heaviness and skewness plot called the NIG-triangle. (wikipedia.org)
- The normal-inverse Gaussian distribution can also be seen as the marginal distribution of the normal-inverse Gaussian process which provides an alternative way of explicitly constructing it. (wikipedia.org)

###### multivariate normal

- The logistic normal distribution is a generalization of the logit-normal distribution to D-dimensional probability vectors by taking a logistic transformation of a multivariate normal distribution. (wikipedia.org)
- In statistics, the matrix normal distribution is a probability distribution that is a generalization of the multivariate normal distribution to matrix-valued random variables. (wikipedia.org)
- The multivariate normal distribution is often used to describe, at least approximately, any set of (possibly) correlated real-valued random variables each of which clusters around a mean value. (wikipedia.org)
- A random vector X = (X1, …, Xk)' is said to have the multivariate normal distribution if it satisfies the following equivalent conditions. (wikipedia.org)
- hence the multivariate normal is a special case of the elliptical distributions. (wikipedia.org)
- The multivariate normal distribution and Wishart distribution are the component distributions out of which this distribution is made. (wikipedia.org)

###### variance

- The log-normal distribution is the maximum entropy probability distribution for a random variate X for which the mean and variance of ln( X ) are specified. (wikipedia.org)
- In its most general form, under some conditions (which include finite variance), it states that averages of samples of observations of random variables independently drawn from independent distributions converge in distribution to the normal, that is, become normally distributed when the number of observations is sufficiently large. (wikipedia.org)
- Both the mean (μ) and variance (σ2) of X in the original normal distribution can be interpreted as the location and scale parameters of Y in the folded distribution. (wikipedia.org)
- Since this is proportional to the variance σ2 of X, σ can be seen as a scale parameter of the new distribution. (wikipedia.org)
- That is, for any constant vector a ∈ Rk, the random variable Y = aTX has a univariate normal distribution, where a univariate normal distribution with zero variance is a point mass on its mean. (wikipedia.org)
- S^2 is variance of sample from normal distribution - what is distribution of cS^2? (mathhelpforum.com)

###### sigma

- mu ,\sigma )={\frac {1}{\sigma {\sqrt {2\pi }}}}\sum _{k=-\infty }^{\infty }\exp \left[{\frac {-(\theta -\mu +2\pi k)^{2}}{2\sigma ^{2}}}\right]} where μ and σ are the mean and standard deviation of the unwrapped distribution, respectively. (wikipedia.org)
- k,1/\theta ^{2})\,d\sigma ^{2}\,d\psi ,} where, in this notation, the distribution-names should be interpreted as meaning the density functions of those distributions. (wikipedia.org)

###### continuous

- In probability theory , a log-normal (or lognormal) distribution is a continuous probability distribution of a random variable whose logarithm is normally distributed . (wikipedia.org)
- It includes all normal and Laplace distributions, and as limiting cases it includes all continuous uniform distributions on bounded intervals of the real line. (wikipedia.org)
- In probability theory and statistics, the skew normal distribution is a continuous probability distribution that generalises the normal distribution to allow for non-zero skewness. (wikipedia.org)
- In a general case the 'parent' normal distributions can have different variances which implies that the joined PDF would not be continuous. (wikipedia.org)
- Like any continuous density curve , the probabilities of observing values within any interval on the normal density are given by the area of the curve above that interval. (yale.edu)
- Theoretically of course, the probability of getting exactly something in a continuous distribution is 0. (mathhelpforum.com)
- In probability theory and statistics, the normal-exponential-gamma distribution (sometimes called the NEG distribution) is a three-parameter family of continuous probability distributions. (wikipedia.org)

###### probability theory

- In probability theory and statistics, the half-normal distribution is a special case of the folded normal distribution. (wikipedia.org)
- In probability theory, a logit-normal distribution is a probability distribution of a random variable whose logit has a normal distribution. (wikipedia.org)
- In probability theory, the family of complex normal distributions characterizes complex random variables whose real and imaginary parts are jointly normal. (wikipedia.org)
- In probability theory and directional statistics, a wrapped normal distribution is a wrapped probability distribution that results from the "wrapping" of the normal distribution around the unit circle. (wikipedia.org)
- In probability theory and statistics, the split normal distribution also known as the two-piece normal distribution results from joining at the mode the corresponding halves of two normal distributions with the same mode but different variances. (wikipedia.org)

###### central limit t

- The normal distribution is useful because of the central limit theorem. (wikipedia.org)
- This same distribution had been discovered by Laplace in 1778 when he derived the extremely important central limit theorem , the topic of a later section of this chapter. (onlinestatbook.com)

###### inverse gamma distri

- has an inverse gamma distribution. (wikipedia.org)

###### univariate

- The complex normal family has three parameters: location parameter μ, covariance matrix Γ, and the relation matrix C. The standard complex normal is the univariate distribution with μ = 0, Γ = 1, and C = 0. (wikipedia.org)
- One definition is that a random vector is said to be k-variate normally distributed if every linear combination of its k components has a univariate normal distribution. (wikipedia.org)
- They assume that each of the principal components has univariate split normal distribution with a different set of parameters μ, σ2 and σ1. (wikipedia.org)

###### generalization

- end{aligned}}} The multivariate generalization of the split normal distribution was proposed by Villani and Larsson. (wikipedia.org)

###### logistic

- However, many other distributions are bell-shaped (such as the Cauchy, Student's t, and logistic distributions). (wikipedia.org)
- It is also known as the logistic normal distribution, which often refers to a multinomial logit version (e.g. (wikipedia.org)
- The logistic normal distribution is a more flexible alternative to the Dirichlet distribution in that it can capture correlations between components of probability vectors. (wikipedia.org)

###### parameters

- are not location and scale parameters for a lognormally distributed random variable X , but they are respectively location and scale parameters for the normally distributed logarithm ln ( X) . The quantity e μ is a scale parameter for the family of lognormal distributions. (wikipedia.org)
- Here λ, α and β are parameters of the joint distribution. (wikipedia.org)

###### density functions

- The distribution is a particular case of a general class of distributions with probability density functions of the form f(x)=2 φ(x) Φ(x) where φ() is any PDF symmetric about zero and Φ() is any CDF whose PDF is symmetric about zero. (wikipedia.org)
- The split normal distribution arises from merging two opposite halves of two probability density functions (PDFs) of normal distributions in their common mode. (wikipedia.org)

###### drawn

- Figure 3 shows the distributions of samples of different sizes drawn at random from normal distributions-few of the small samples look like a normal distribution, but the similarity increases as the sample size increases. (bmj.com)

###### binomial distribution

- In the chapter on probability, we saw that the binomial distribution could be used to solve problems such as 'If a fair coin is flipped 100 times, what is the probability of getting 60 or more heads? (onlinestatbook.com)
- de Moivre noted that when the number of events (coin flips) increased, the shape of the binomial distribution approached a very smooth curve. (onlinestatbook.com)
- The normal approximation to the binomial distribution for 12 coin flips. (onlinestatbook.com)
- As I was thinking I might have to use a binomial distribution with successes and failures but if that other way works it would be much faster? (mathhelpforum.com)
- Prob that at least one is rejected is 1 - prob that none are rejected = 1-(1-0.0786)^20, which is what the binomial distribution would give. (mathhelpforum.com)

###### bell curve

- The exhibit below illustrates a simple process that gives rise to the familiar "bell curve" of the normal distribution. (uky.edu)
- The normal distribution is sometimes informally called the bell curve. (wikipedia.org)
- A normal distribution or bell curve is arranged symmetrically on either side of the mean (sometimes the median is used). (reference.com)

###### boldsymbol

- boldsymbol {\Psi }},\nu )} has an inverse Wishart distribution. (wikipedia.org)

###### mean

- Thus a proportion is also a mean and will follow a normal distribution. (bmj.com)
- Thus, the half-normal distribution is a fold at the mean of an ordinary normal distribution with mean zero. (wikipedia.org)
- The entropy of the half-normal distribution is exactly one bit less the entropy of a zero-mean normal distribution with the same second moment about 0. (wikipedia.org)
- It also coincides with a zero-mean normal distribution truncated from below at zero (see truncated normal distribution) If Y has a half-normal distribution, then (Y/σ)2 has a chi square distribution with 1 degree of freedom, i.e. (wikipedia.org)
- The 'circularly-symmetric normal distribution corresponds to the case of zero mean and zero relation matrix, μ=0, C=0. (wikipedia.org)
- The Standard Normal curve, shown here, has mean 0 and standard deviation 1. (yale.edu)
- About 95% of the observations will fall within 2 standard deviations of the mean, which is the interval (-2,2) for the standard normal, and about 99.7% of the observations will fall within 3 standard deviations of the mean, which corresponds to the interval (-3,3) in this case. (yale.edu)
- For the first 10 sorted observations, the table below displays the original temperature values in the first column, standardized values in the second column (calculated by subtracting the mean 98.249 and dividing by the standard deviation 0.733), and corresponding normal scores in the third column. (yale.edu)
- The teacher decides which grade represents the mean, or median, and then assigns grades by following the normal distribution. (reference.com)
- A skewed distribution is one which is not symmetrical about the mean, or average. (reference.com)
- where μ is the mean of the distribution and σ the standard deviation. (ethz.ch)
- A bunch of thermometers give a reading of 0 degrees C that follow a normal distribution with a mean 0 degrees C and a standard deviation of 1 degree C. (mathhelpforum.com)
- By definition for a normal distribution the mean is the mode and median value, so there was no need to calculate the probability of someone being less then 73 inches. (mathhelpforum.com)
- Assume you have a normal distribution with a mean of 7.5 and standard deviation of 3. (mathhelpforum.com)
- In a normal distribution, what percent of data are above the mean? (mathhelpforum.com)
- The weight of 1000 students in a secondary school has a normal distribution with a mean of 68.5kg and a standard deviation of 2.7kg. (mathhelpforum.com)
- It is the conjugate prior of a normal distribution with unknown mean and precision. (wikipedia.org)

###### exponential power distri

- Known also as the exponential power distribution, or the generalized error distribution, this is a parametric family of symmetric distributions. (wikipedia.org)

###### curve

- You are provided with the probability densities, that will define the normal curve we plot and will use Excel functions and charts to explore the distrbution family. (lynda.com)
- On the spreadsheet, column E has the values that go on the X axis of the graph that we'll create, and column F will hold the F of x values, the probability densities that will define the normal curve we plot. (lynda.com)
- This is exactly what he did, and the curve he discovered is now called the 'normal curve. (onlinestatbook.com)
- The smooth curve is the normal distribution. (onlinestatbook.com)
- The importance of the normal curve stems primarily from the fact that the distributions of many natural phenomena are at least approximately normally distributed. (onlinestatbook.com)
- For example, the probability of observing a value less than or equal to zero on the standard normal density curve is 0.5, since exactly half of the area of the density curve lies to the left of zero. (yale.edu)
- This arrangement forms a bell-shaped pattern called a normal curve, according to Regents Exam Prep Center. (reference.com)

###### circularly-symmetric

- The circularly symmetric version of the complex normal distribution has a slightly different form. (wikipedia.org)

###### probabilities

- This is a short Java program to calculate probabilities (and points) under the normal distribution. (uvm.edu)
- Instead, the probabilities for the standard normal distribution are given by tabulated values (found in Table A in Moore and McCabe or in any statistical software). (yale.edu)
- Assuming that the temperature data are normally distributed, converting the data into standard normal, or "Z," values allows for the calculation of cumulative probabilities for the temperatures (the probability that a value less than or equal to the given value will be observed). (yale.edu)
- In MINITAB, the "CDF" command calculates the cumulative probabilities for standard normal data, or the probability that a value less than or equal to a given value will be observed. (yale.edu)

###### Laplace

- Laplace showed that even if a distribution is not normally distributed, the means of repeated samples from the distribution would be very nearly normally distributed, and that the larger the sample size, the closer the distribution of means would be to a normal distribution. (onlinestatbook.com)

###### approximation

- Use of normal distribution as an approximation to poisson distribution. (mathhelpforum.com)

###### Examples

- Examples of binomial distributions. (onlinestatbook.com)

###### symmetric

- Circular symmetric complex normal random variables are used extensively in signal processing, and are sometimes referred to as just complex normal in signal processing literature. (wikipedia.org)

###### case

- This is of course something to be expected, since, in this case, the folded normal converges to the normal distribution. (wikipedia.org)
- The covariance matrix is allowed to be singular (in which case the corresponding distribution has no density). (wikipedia.org)
- In any case, use your standard normal tables in reverse. (mathhelpforum.com)
- This class is closed under affine transformations, since it is a particular case of the Generalized hyperbolic distribution, which has the same property. (wikipedia.org)

###### Likewise

- Likewise, if Y has a normal distribution, then the exponential function of Y , X = exp( Y ) , has a log-normal distribution. (wikipedia.org)

###### independently

- Independently, the mathematicians Adrain in 1808 and Gauss in 1809 developed the formula for the normal distribution and showed that errors were fit well by this distribution. (onlinestatbook.com)

###### quantile

- The normality of the data may be evaluated by using the MINITAB "NSCORES" command to calculate the normal scores for the data, then plotting the observed data against the normal quantile values. (yale.edu)
- The standardized values in the second column and the corresponding normal quantile scores are very similar, indicating that the temperature data seem to fit a normal distribution. (yale.edu)
- The plot of these columns, with the temperature values on the horizontal axis and the normal quantile scores on the vertical axis, is shown to the right (the two scales in the horizontal axis provide original and standardized values). (yale.edu)

###### normally distributed random variable

- In probability and statistics, the truncated normal distribution is the probability distribution derived from that of a normally distributed random variable by bounding the random variable from either below or above (or both). (wikipedia.org)

###### parameter

- Both families add a shape parameter to the normal distribution. (wikipedia.org)

###### assume

- Most statistical procedures for testing differences between means assume normal distributions. (onlinestatbook.com)

###### reduces

- This expression reduces to the CDF of the half-normal distribution when μ = 0. (wikipedia.org)
- This can be understood intuitively since the magnitude operator reduces information by one bit (if the probability distribution at its input is even). (wikipedia.org)

###### statistical

- You can easily generate data from a normal distribution using any of the commonly available statistical packages. (uvm.edu)
- A log-normal process is the statistical realization of the multiplicative product of many independent random variables , each of which is positive. (wikipedia.org)

###### functions

- Specifically, we'll use Excel functions and graphing to explore the normal distribution family. (lynda.com)

###### subclass

- The NIG distribution was noted by Blaesild in 1977 as a subclass of the generalised hyperbolic distribution discovered by Ole Barndorff-Nielsen, in the next year Barndorff-Nielsen published the NIG in another paper. (wikipedia.org)

###### statistics

- Normal distributions are important in statistics and are often used in the natural and social sciences to represent real-valued random variables whose distributions are not known. (wikipedia.org)
- Although widely referred to in statistics, the normal distribution remains a mysterious concept to many. (bmj.com)
- The normal distribution has another essential place in statistics. (bmj.com)
- It is closely approximated by the von Mises distribution, which, due to its mathematical simplicity and tractability, is the most commonly used distribution in directional statistics. (wikipedia.org)
- The truncated normal distribution has wide applications in statistics and econometrics. (wikipedia.org)

###### standard normal distr

- Then use your Four-Figure Standard Normal Distribution Tables. (mathhelpforum.com)
- Z follows a standard normal distribution. (mathhelpforum.com)

###### Given

- Approximations to this distribution that are easier to manipulate mathematically have been given by Ashour and Abdel-Hamid (2010) and by Mudholkar and Hutson (2000). (wikipedia.org)

###### gamma distribution

- where this means that T has a gamma distribution. (wikipedia.org)
- The normal-gamma distribution is the one-dimensional equivalent. (wikipedia.org)

###### measurement

- Physical quantities that are expected to be the sum of many independent processes (such as measurement errors) often have distributions that are nearly normal. (wikipedia.org)
- One of the first applications of the normal distribution was to the analysis of errors of measurement made in astronomical observations, errors that occurred because of imperfect instruments and imperfect observers. (onlinestatbook.com)

###### often

- As a consequence, when we have samples of hundreds of observations we can often ignore the distribution of the data. (bmj.com)

###### interval

- Suppose, for example, we are interested in the probability of observing values within the standard normal interval (0,0.5). (yale.edu)
- The probability of the normal interval (0, 0.5) is equal to 0.6915 - 0.5 = 0.1915. (yale.edu)

###### approximate

- Well, the final position of each ball is determined by many (here only 8) independent, random events of whether to drop to the left or the right of the pin, thus the (approximate) normal distribution. (uky.edu)
- It is possible to fit the generalized normal distribution adopting an approximate maximum likelihood method. (wikipedia.org)

###### follows

- follows a half-normal distribution. (wikipedia.org)
- The modulus of a complex normal random variable follows a Hoyt distribution. (wikipedia.org)
- The time until the first failure occurred in supplies ink to a particular printer brand, follows a normal distribution with μ=1500 and standard deviation(σ) 20 hours of operation. (physicsforums.com)

###### follow a normal distribution

- This plot indicates that the data appear to follow a normal distribution, with only the three largest values deviating from a straight diagonal line. (yale.edu)