This site gives an explanation, a definition and an example of chi-square goodness of fit test. Topics include chi-square test statistics, tests for discrete and continuous distributions.
This applet generates a graph of the sampling distribution of sample means and displays the probabilities associated with that distribution. Users enter the mean and standard deviation of the source population and the size of the samples. The applet also calculates the standard error of the sample means.
This page generates a graph of the sampling distribution of the difference between two means and displays the probabilities associated with that distribution. Users enter the population standard deviation and the sample sizes, Na and Nb. The applet also calculates the standard error of the sample mean difference.