WISE's website organises a large amount of statistics resources available on the web into one central place. It also is home to a series of interactive, sequenced tutorials on key statistical concepts. The tutorials use dynamic applets that allow the user to explore relationships on their own. Guided exercises are designed to help the learner to take full advantage of the applets to gain a deeper understanding of the concepts and logic that underlie much of inferential statistics. On WISE, you can find WISE tutorials, WISE applets, excel downloads, teaching papers, quick guides, and publications.
A simple random sample (SRS) is the most basic probabilistic option used for creating a sample from a population. Each SRS is made of individuals drawn from a larger population (represented by the variable N), completely at random. As a result, said individuals have an equal chance of being selected throughout the sampling process. The benefit of SRS is that as a result, the investigator is guaranteed to choose a sample which is representative of the population, which ensures statistically valid conclusions.