This experiment carried at Wave 4 tested whether response rates could be improved if respondents are encouraged to telephone their interviewer in advance of fieldwork to set an appointment to be interviewed. A portion of the sample was given an incentive for setting and keeping an appointment. The incentive was £5 if the respondent called to make an appointment and was interviewed.
All addresses were allocated to treatment groups. However, only prior wave productive households were included in the offer and the refreshment sample and suspected split-households were excluded.
The controlling variable is _ip d_ff_apptsw4 on record d_hhsamp whereas d_ff_samplecat on record d_hhsamp_ip contains the actual manipulation as used in field at ip4 after prior unproductive and splits were excluded. d_ff_apptsw4 is coded as follows:
1 Early-bird offer, with incentive
2 Early-bird offer, no incentive
3 No offer
d_ff_samplecat is coded as follows:
1 Early-bird offer, with incentive
2 Early-bird offer, no incentive
3 No offer
4 Refreshment sample
In addition, information about the appointment made and whether it was kept was recorded for all sample members. Variables containing this information are d_conmth, d_ebmover, d_conoc, d_apptoc, d_apptday2, d_ebend, d_issue_num, d_conday, d_ebmovtype, d_apptmth, d_firstappt, d_appttime2, d_ebintro, d_conmethod, d_ebmovconf, d_apptday, d_conperson2, d_apptoc2, d_ebcontact, d_conperson, d_ebaddupdate, d_appttime, d_apptmth2, and d_ebothinf on record d_admineb_ip.
