Analysis of Large-Scale Social Surveys 1
Large-scale social surveys are an important source of information for a wide range of topics. In analyzing such surveys, it is important to be aware of the complexity of the sampling design and the data adjustments that are used by survey organizations, including weighting to adjust for diierences between sample and population and imputation to ll in missing responses. For estimating population means and proportions, the analyst should calculate weighted averages, using survey weights. In regression analysis, it is best to include, among the predictors, the variables that are used in the design and the weighting. Hierarchical models can be used to obtain inferences for small subpopulations. In general, analyzing survey data as if they had been obtained through simple random sampling can result in biased point estimates and underestimated standard errors. These calculations can often be adjusted reasonably well by using design eeects reported in the survey documentation or in previous analyses. For more involved analysis, it is advisable to use statistical packages that are speciically designed to correctly handle complex survey data.