Table 1 Millennium Cohort Study follow-up survey methods between 2004–2006 and 2014–2016
From: Survey response over 15 years of follow-up in the Millennium Cohort Study
Follow-up Survey Cycle Years | ||||
|---|---|---|---|---|
2004—2006 | 2007—2008 | 2011—2013 | 2014—2016 | |
Months cycle was open | 20 | 19 | 24 | 23 |
Primer email | No | No | No | Yes |
Number of reminder emailsa | 10 | 23 | 22 | 21 |
Number of reminder postcardsb | 4 | 4 | 3 | 3 |
Number of reminder automated phone message | 0 | 3 | 1 | 0 |
Commemorative and reminder emails and postcards (Memorial Day and Veterans Day) | Yes | Yes | Yes | Yes |
Endorsement letter | No | No | Yesc | Yesc |
Pre-incentive letter | No | No | No | 1 |
Newsletter | No | No | No | 2 |
Desktop calendar | No | No | No | 1 |
Web survey completion post-incentive | Choice between hat, t-shirt, or phone card | Choice between hat, t-shirt, or phone card | Choice between $5 gift card to Starbucks, Walmart, Amazon, or Subway, hat, coin, or none; | Choice between $5 gift card to Starbucks, Walmart, Amazon or Subway, hat, or none |
Pre-incentive | None | Gift card sent to late paper survey responders at end of cycle | $5 for incomplete surveys at end of cycle | Randomly assigned experiment: magnet; $2 bill; gift card; lottery entry for an iPad; or letter/no pre-incentive |
Number of paper questionnaires | 4 | 5 | 5 | 4 |
Month of survey cycle the paper questionnaires were mailed | 2, 4, 6, 12 | 1, 3, 6, 11, 15 | 3, 5, 9, 17, 19 | 3, 7, 12, 15 |
Number of short paper (2 page) questionnaires mailed | 0 | 0 | 0 | 2 |
Month of survey cycle the short paper (2 page) questionnaires were mailed | - | - | - | 18, 20 |