The left panel shows a population of scores. Click to calculate the mean and standard deviation of the
population. Then click "Sample" to select a random sample. The sample will be listed and the
mean and standard deviation of the sample will be calculated. The sample means are listed in the
right panel. The mean and standard deviation of the sample means is calculated. You can compare them
with their theoretical values shown below. Keeping sampling and you will see the discrepency between the
observed and theoretical values lessen. You can change the sample size to see how this affects things.