Targeted appeals for participation in letters to panel survey members

Summary

Previous research into survey invitation letters and prenotification letters has sought to identify optimal features of a standard letter that can be sent to all sample members. In the spirit of adaptive design, this study seeks to establish whether it can be advantageous to target different versions of a letter to different sample subgroups. Specifically, a paragraph intended to heighten perceptions of relevance of the survey is varied among six subgroups in a panel survey. Random allocation to control and treatment groups is crossed with variants of two other design features: time in sample and data collection mode. This enables analysis of the effects of the targeted letter in different survey contexts. The targeted version of the letter improved response rates for two operationally important low-response propensity groups, but only in certain survey design contexts.