Data implementation procedures for this study52
| Week | Mail preference | Web preference |
|---|---|---|
| 1 | Standard introducing letter | Standard introducing postal letter |
| 2 | Invitation letter including consent statement, mail questionnaire, incentive and return envelope | Invitation email letter including consent statement, link to the survey, incentive and web survey instructions |
| 3 | Thank you postcard or reminder postcard | Thank you or reminder email with link to the survey |
| 4 | Replacement questionnaire and return envelope with cover letter including link to the survey for web options to the non-responders | Reminder email to the non-responders with link to survey and web survey instructions accompanied by mail questionnaire and return envelope for the mail option |