Abstract

Many national surveys include screening interviews intended to identify  members of the eligible population or members of rare subgroups slated for oversampling. Underreporting of members of these groups drives up survey costs and may introduce bias into the estimates. There is evidence that members of the target populations are sometimes underreported in screening interviews. Interestingly members of these same groups are often well covered in surveys that do not particularly screen for them. One of the best documented instances of such a screening shortfall occurred in the National Longitudinal Survey of Youth, 1997 Cohort, with a coverage ratio of only about 70 percent of
the targeted age group. All other age groups have rates above 90 percent. Such screening shortfalls could reflect respondent motivation to screen out rather than refuse (and be subject to conversion attempts). They could also reflect on interviewer motivations, for field interviewers are often graded based on their nonreponse rate but eligibility rates are not held against them.

This project is funded by the U.S. National Science Foundation an includes a telephone survey in which we varied experimentally two factors believed to affect likelihood of
motivated underreporting through the sample units and one factor at the interviewer level. (1) The amount of information given about the target opulation in the advanced letters. (2) The format of the screener tself, with full household roasters being tested against screening uestions that asks explicitly about the target population. (3) Interviewers were assigned to different payment schemes that vary the monetary incentive for an interviewer to complete a full interview or just the screener. Our design allows the estimation of main effects of
each of these factors as well as their interactions. We expect to see differences in eligibility rates across payment incentive groups if the interviewers contribute to the motivated underreporting effects seen in the literature.