IBM SPSS COMPLEX SAMPLES 19 manual Tree Controls for Navigating the Analysis Wizard

21

Preparing a Complex Sample for Analysis

This step allows you to identify the stratification and clustering variables and define sample weights. You can also provide a label for the stage.

Strata. The cross-classification of stratification variables defines distinct subpopulations, or strata. Your total sample represents the combination of independent samples from each stratum.

Clusters. Cluster variables define groups of observational units, or clusters. Samples drawn in multiple stages select clusters in the earlier stages and then subsample units from the selected clusters. When analyzing a data file obtained by sampling clusters with replacement, you should include the duplication index as a cluster variable.

Sample Weight. You must provide sample weights in the first stage. Sample weights are computed automatically for subsequent stages of the current design.

Stage Label. You can specify an optional string label for each stage. This is used in the output to help identify stagewise information.

Note: The source variable list has the same contents across steps of the Wizard. In other words, variables removed from the source list in a particular step are removed from the list in all steps. Variables returned to the source list show up in all steps.

Tree Controls for Navigating the Analysis Wizard

At the left side of each step of the Analysis Wizard is an outline of all the steps. You can navigate the Wizard by clicking on the name of an enabled step in the outline. Steps are enabled as long as all previous steps are valid—that is, as long as each previous step has been given the minimum required specifications for that step. For more information on why a given step may be invalid, see the Help for individual steps.