ABSTRACT
This chapter discusses the validity of the conclusions that one is likely to draw from a given sampling method, and the relative efficiencies of various sampling methods. It presents an intuitive introduction to the basic ideas in sampling. A sample is the collection of observations for which researcher have data with which they are going to work. Almost any set of observations for which researcher have data constitutes a sample. A randomly-chosen sample is a fair sample; it would be a fair bet that any member of the universe would be picked for the sample, compared to any other member of the universe. Some studies require a sample of personal interviews with relatively rare individuals—people that have been to Africa, or blind people, or sociologists, or families with four sons. The term sampling error refers to the discrepancy between the estimate one obtains from a given sample, and the estimate that one would obtain from a very, very large sample.
