This experiment carried at Wave 4 examined whether additional information included in the re-issue letter would help boost response at this stage. All households were allocated within PSU to a treatment group, but only re-issued households were included in the experiment. Version A received the standard re-issue letter, and Version B received the re-issue letter plus an additional leaflet explaining the importance of participating in the study.
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 Standard re-issue letter
2 Letter plus leaflet
