AS/A2 Stats 1 Stats 2

S3 Topic 4: Goodness of fit and contingency tables
The uniform and Normal distributions
The applet displays a window that shows the expected frequencies for each of 10 intervals based on a sample size of 100. The left side of the window shows the frequencies expected if the distribution being sampled is normal. Notice that the distribution is symmetric with higher expected frequencies for the middle intervals than for the tails. The sum of the expected frequencies is 100. On the right side are shown the expected frequencies if the distribution being sampled is uniform. The expected frequency is the same (10) for each interval. By default, the applet samples from a normal distribution. Press the sample button and 100 samples will be taken and the frequencies for each of the intervals computed and displayed as the observed frequencies. Deviations from the expected frequencies are computed for the expected frequencies based on the normal and based on the uniform distribution. Since the samples are from a normal distribution, the observed frequencies should be closer to the expected frequencies based on a normal distribution than based on a uniform distribution.

an applet from the Rice Virtual Lab in Statistics