This experiment examined whether targeting respondents by sending email invitations to complete the survey on different days affects response outcomes and data quality. The targeted component reflects the idea that people may be more likely to respond on particular days, possibly due to preference or time availability.
This experiment involved only households in the mixed-mode sample of the IP who had been in the mixed-mode in previous waves. Half of these households were assigned to the control condition, where normal contact procedures were followed. The other half of the mixed-mode sample were assigned to the experimental condition and everyone in the household was sent an email invitation on the day predicted to be more likely to lead to response. This prediction sought to take advantage of the longitudinal context of the survey, where there is a wide range of information on panel household members and their response behaviour. Knowledge of the response behaviour was based on the paradata collected in the data collection process. Paradata from IP waves 5-8 was used to identify likelihood of respondent preference for a given day of the week depending on when the household interview was completed during the week in the past.
It was expected that an invitation email sent when the panel household was more likely to respond (have time to do so) could increase the chance of participation. It was also expected that targeted timings could improve response speed, as sample households were expected to respond more promptly. Individuals within these experimental households who did not initially respond were sent a reminder email based on their individually expressed preferred day, estimated based on response to the individual questionnaire.
The allocation of respondents for this experiment is controlled by the following variables:
i_ff_maildayhhw9 in file i_hhsamp_ip: Day of email invitation to the entire household
0 Sunday
1 Monday
2 Tuesday
3 Wednesday
4 Thursday
5 Friday
6 Saturday
7 Control
8 Unassigned
i_ff_maildayindw9 in file i_indsamp_ip:Day of email reminder to nonresponding individuals
0 Sunday
1 Monday
2 Tuesday
3 Wednesday
4 Thursday
5 Friday
6 Saturday
7 Control
8 Unassigned
