Table 2 Changes made in each wave of the study
Wave | Time period | Description of questionnaire distribution | Changes between waves | |
|---|---|---|---|---|
1st attempt | 2nd attempt | |||
Wave 1 | 4 months | Questionnaire and cover letter (V1) sent via email or post (stamped addressed envelope included) | Questionnaire resent via post | - |
Wave 2 | 4 months | Questionnaire layout updated and cover letter (V2), sent via email or post (stamped addressed envelope included) | Questionnaire resent via post | Cover letter updated to utilise behaviour change techniques designed to increase response, free pen included, questionnaire updated |
Wave 3 | 4 months | Questionnaire and cover letter (V2), sent via email or post (stamped addressed envelope included) | Reminder by: Postcard Telephone call Questionnaire resent | RCT conducted for those who did not complete the questionnaire on the first send out to determine if one reminder was more effective or reduced bias |