What was learned from the SPD Exploratory Attrition Study and the use of incentives?
Addressing concern about the SPD response rates, the Census Bureau conducted an Exploratory Attrition Study (20) to assess the extent to which nonrespondents could be brought back into the sample. Other longitudinal surveys (such as the PSID and NLS-Y) have gone back to early panel nonrespondents and successfully brought them back into sample. A key aspect of this experiment was to test the effectiveness of paying incentives to nonrespondents to encourage people who had not responded as long as 5 or 6 years earlier to re-enter the sample and respond to a current questionnaire. The project focused on people at or below 200 percent of the poverty threshold, because they are of interest in studies of welfare reform and their attrition is much greater than that of the higher-income population. Possible reasons why attrition is a problem for the SPD include the fact that SPD households will be followed much longer than SIPP households–10 years for SPD versus 4 years for the 1996 SIPP panel
