In Wave 5, the content of the advance letters was varied to test theories about how people can be persuaded to take part in surveys. A two factor manipulation tested the effects of persuasion ideas, being a helpful person and being similar to other respondents. In the advance letters, one half of sample members received an additional sentence “your responses in previous survey show that you are a helpful person”; the other half of the sample had no such sentence. Second, one-half the sample received the sentence “almost everyone like you responded in the last wave of the survey” and the other half received no such sentence:
1 Helpful person
2 Respondents like you
3 Helpful person, Respondent like you
4 Control group
Within PSUs, households were randomly allocated to treatment groups and all eligible respondents in the household were treated the same. The controlling variable is e_ff_persuasionw5 on the record e_hhsamp_ip.
In addition, the self-completion questionnaire has items to assess self-rated helpfulness, conformity, and preference for consistency as potentially useful predictors of response status in future waves.
