Central Limit Theorem: A sampling distribution of the mean is approximately normally distributed if the sample size is sufficiently large. This is true no matter what the population distribution is.

Here are four programs that demonstrate sampling distributions. For each one, a "population" of 20,000 elements is established. The user selects a sample size and random samples are drawn from the ...

This paper presents the results of a limited investigation which brings into focus the difficulties encountered in developing exact distribution-free methods for stratified simple random sampling. It ...

There are some limitations of using a quadrat. Human judgement can be an issue when using a quadrat. For example, some plants may be partially inside/outside a quadrat so there are basic rules that ...

Andrew Gelman, a professor in the departments of statistics and political science at Columbia University, explains. A "3 percent margin of error" means that there is a 95 percent chance that the ...