The sampling workbook is designed to help students understand what happens when one takes a sample. A variety of known distributions are sampled, the students being able to choose the sample size. Each time the sample is shown visually and the mean calculated.

Simulating confidence intervals for a population mean

Three further spreadsheets enable students to take repeated samples of any size up to 20 from known distributions and to build up the distribution of the sample means.

Other spreadsheets show how a confidence interval is calculated and finally the spreadsheet shown on this page enables students to appreciate what is meant by a confidence interval - showing how often they do, or don't, include the population mean which is represented by the dotted line. Students can change any of the values in blue, for example the percentage degree of confidence, P, or sample size, n, to see what happens.

The Workbook SAMP.XLS contains:

• Sampling from a Normal population
• Sampling from a Uniform population
• Sampling from an Exponential population
• Sampling from a Normal population showing the distribution of the sample means
• Sampling from a Uniform population showing the sampling distribution of the means
• Sampling from an Exponential population showing the sampling distribution of the means
• Calculating a confidence interval for a population mean
• Calculating a confidence interval for a population proportion
• Simulating confidence intervals for a population mean