Are there differences in responses to social identity questions in face-to-face versus telephone interviews? Results of an experiment on a longitudinal survey

This paper investigates the effect of interview mode (telephone versus face-to-face) on responses to a 13-item module of identity questions covering distinct domains. With increasing moves towards mixed-mode implementation, especially in longitudinal surveys, establishing whether mode effects are likely to influence findings is of practical value. A growing number of studies explore mode effects; but the potential impact of mode on identity questions has not been investigated, even though such questions are increasingly being asked in multi-topic surveys. Adjusting for selection, we find little evidence for specific mode effects. The exception is responses on political identity: telephone responders are eight percentage points more likely to consider politics important to their identity. We do not find differences in data quality as measured by item non-response, straightlining, primacy and recency effects across modes. We conclude that mode effects are small for identity questions.