Nonresponse versus measurement error: Are reluctant respondents worth pursuing?

To increase response rates, survey researchers intensify their efforts to bring sampled persons into the respondent pool. The question is whether or not “reluctant” survey respondents provide answers of lower quality than “eager” respondents. We define eager respondents as persons who respond to the first round of a mail survey, and reluctant respondents as persons who respond in later rounds. We used a multitrait-multimethod (MTMM) design, which allows statistical separation of substantive or trait variance, method variance, and error variance. The results show that the measurement structure does not differ between eager and reluctant respondents. There was also no systematic difference in the reliability and validity estimates for both groups.