Distributions
This section contains the following items. Details for each can be found by scrolling down the page.

 °
 Sampling Distribution Generators: for Binomial; Poisson; ChiSquare; Student's t; Pearson r; FRatios; Normal; Sample Means; Sample Mean Differences

°
 Central Limit Theorem [Demo]

°
 ztoP Calculator

°
 Standard Error of Sample Means

°
 Standard Error of the Difference between the Means of Two Samples

Sampling Distribution Generators. These units generate a graphic and numerical display of the properties of the indicated sampling distribution.
 Binomial Distributions. For any values of p and q, and for values of n between 1 and 40, inclusive.

Poisson Distributions for the approximation of binomial sampling distributions in the case where p is quite small (<.02) and n is fairly large.

Poisson Distributions with a specified mean. As the page opens you will be prompted to enter the mean of the distribution (between 0.01 and 20.0, inclusive). [See also, under Frequency Data, the unit entitled "Fittting an Observed Frequency Distribution to the Closest Poisson Distribution."]

ChiSquare Distributions. For values of df between 1 and 20, inclusive.

tDistributions. For values of df between 4 and 200, inclusive.

Distributions of r, the Pearson product moment correlation coefficient, for values of n>6.

FDistributions. For any value of df_{numerator} and for values of df_{denominator}>5.

Normal Distributions.^{T}For a unit normal distribution, with M=0 and SD=±1, enter 0 and 1 at the prompt. For a distribution with M=100 and SD=±15, enter 100 and 15. And so forth.

Distributions of Sample Means. Enter the mean and standard deviation of the source population and the size of the samples.

Distributions of Sample Mean Differences, for independent samples of sizes n_{a} and n_{b}. At the prompt, enter the standard deviation of the source population and the values of n_{a} and n_{b}.

Central Limit Theorem. A demonstration pertaining to the question: "Why is the normal distribution so very 'normal'?" [Note that this demo might not work properly with older browsers. Please also note that this page might take a moment to load.]
z to P Calculator. Calculates the areas under the curve of the normal distribution falling to the left of
—z, to the right of +z, and between
—z and +z.
Standard Error of Sample Means. For samples of size n, randomly drawn from a normally distributed source population with specified mean and standard deviation.
Standard Error of the Difference Between the Means of Two Samples. For samples of sizes n
_{a} and n
_{b}, randomly and independently drawn from a normally distributed source population with specified standard deviation.