Research design: sampling techniques.

Conditions affecting the decision of whether to take a census or a sample; the major types of sampling procedures, both probability and nonprobability;; and the statistical approaches to sample size determination for simple random samples are discussed. An overview of selected terms and symbols used in sampling literature and a checklist of basic questions to guide a researcher interested in using sampling for a study are provided. While the researcher can control sampling error by increasing the sample size, the concern should be the magnitude of the total error for the study (both sampling and nonsampling errors).