Table 1.
Enrollment and completion rates of Tiers I, II, and III
| Targeted enrollment; (% recruited northern, central) | Actual enrollment (northern, central) | Full data completion (northern, central) | Only partial data completion (northern, central) | Only minimal data completion (northern, central) | |
|---|---|---|---|---|---|
| Tier I: year 1 only | 5 survey elements | 3-4 survey elements | 1-2 survey elements | ||
| n = 750 | n = 655 | n = 580 | n = 31 | n = 39 | |
| (26%,32%) | (499, 156) | (87%,95%) | (6%,2%) | (7%,3%) | |
| Tier I: longitudinal (years 1-3) | 3 years | 2 years | ≤1 year | ||
| See above | See above | n = 252 | n = 182 | n = 221 | |
| (38%,41%) | (25%,37%) | (37%,22%) | |||
| Tier II: 15/18 monthsa | 15-18 monthly surveys | 10-14 monthly surveys | 1-9 monthly surveys | ||
| n = 250 | n = 250 | 95b | 26 | 129 | |
| (77%,75%) | (186, 64) | (29%,63%) | (11%,9%) | (60%,28%) | |
| Tier III: 8 visits over 4 seasonsb | 4 collection periodsc | 2-3 collection periods | 1 collection period | ||
| n = 40 | n = 47 | n = 40 | n = 4 | n = 3 | |
| (34%,52%) | (30, 17) | (90%,76%) | (7%,12%) | (3%,12%) | |
a Full completion depended upon timing of enrollment into tier 2 as it was modified from 15 to 18 months.
b Includes participants (n = 53) who attempted to complete surveys but encountered issues with the internet survey.
c Each collection consisted of a set-up visit and a take-down visit at the beginning and end of a week. The goal was for four collection periods across a 16 month period.