WESVAR: SOFTWARE FOR COMPLEX SURVEY DATA ANALYSIS

ABSTRACT Nearly all surveys use complex sample designs to collect data and these data are frequently used for statistical analyses beyond the estimation of simple descriptive parameters of the target population. Many procedures available in popular statistical software packages are not appropriate for this purpose because the analyses are based on the assumption that the sample has been drawn with simple random sampling. Therefore, the results of the analyses conducted using these software packages would not be valid when the sample design incorporates multistage sampling, stratification, or clustering. We discuss WesVar software that computes estimates and replication variance estimates by properly reflecting complex sampling and estimation procedures. We also illustrate the WesVar features by using data from two Westat surveys that employ complex sample designs: the Third International Mathematics and Science Study (TIMSS), and the National Health and Nutrition Examination Survey (NHANES).