From Concurrent to Push-To-Web Mixed-Mode: Experimental Design Change in the German Social Cohesion Panel

Research shows that concurrent and sequential self-administered mixed-mode designs both have advantages and disadvantages in terms of panel survey recruitment and maintenance. Since concurrent mixed-mode designs usually achieve higher initial response rates at lower bias than sequential mixed-mode designs, the former may be ideal for panel recruitment. However, concurrent designs produced high share of paper respondents relative to web respondents. Since these paper respondents have been found to be at higher risk of attrition, cause higher data collection costs, and slow down the fieldwork process, sequential mixed-mode designs may be more practical in the regular course of the panel study after recruitment. Our study provides experimental evidence on the effect of switching a panel study from concurrent to sequential mixed-mode design after the panel recruitment. Results show that this switch significantly increases the share of online respondents without harming response rates. Respondents who are pushed to the web by the design change differ significantly from respondents who continue to participate via paper questionnaires with regard to a number of socio-digital inequality correlates. This suggests that, while the share of online respondents can be increased through mode sequencing, keeping the paper mail mode option is vital for ensuring continued representation of societal subgroups.