Section 2.4 of this report briefly described features of sample designs that affect the sampling errors and thus contribute to design effects. It was also noted that design effects can differ among statistics gathered in a survey, sometimes dramatically. As a basis for decision-making, we have chosen to use an average design effect for each survey, one that is approximately midway between the high and low values. In a few cases, we have indicated an additional design effect that applies to specific race/ethnic groups. However, an analyst who is concerned with a specific subject in a survey might prefer to use a different design effect that is more appropriate to the items to be studied. This report cannot take into account all possible analyses that could be carried out. We have tried to include enough information to permit modifications of the results for special subpopulations or items.
The design effects shown in Table 3-2 come from a number of sources (see Appendix A). Wherever possible, we have used published reports. These reports usually do not show design effects, as such, but the information on sampling errors makes it possible to calculate average design effects. When published reports with the required information were not available, the design effects were estimated from the descriptions of the sample design or through discussions with statisticians at the agencies sponsoring the surveys.