More Clarification, Less Item Nonresponse in Establishment Surveys? A Split-Ballot Experiment

The IAB Job Vacancy Survey of the German Institute for Employment Research collects detailed information on job search and vacancy durations for an establishment’s last successful hiring process. The duration questions themselves are burdensome for respondents to answer as they ask for precise dates of the earliest possible hiring for the vacancy, the start of the personnel search, and the decision to hire the selected applicant. Consequently, the nonresponse rates for these items have been relatively high over the years (up to 21 percent). In an effort to reduce item nonresponse, a split-ballot experiment was conducted to test the strategy of providing additional clarifying information and examples to assist respondents in answering the date questions. The results revealed a backfiring effect. Although there was evidence that respondents read the additional clarifying information, this led to even more item nonresponse and lower data quality compared to the control group. Additionally, we observed a negative spillover effect with regard to item nonresponse on a subsequent (non-treated) question. We conclude this article by discussing possible causes of these results and suggestions for further research.