Table 3.
Willingness to participate, participation rates, and conditional participation rates in trial 1 and 2
| Invitation formats | No choice | Choice | ||||
|---|---|---|---|---|---|---|
| TRIAL 1 | interview (n = 198) | interview or questionnaire (n = 193) | X 2 | df | p | RR (95%CI) |
| Participation rate | 130 (66%) | 125 (65%) | 0.03 | 1 | 0.853 | 0.98 (0.74 - 1.28) |
| Conditional participation rate | 130 (90%) | 125 (72%) | 15.65 | 1 | <.01 | 0.37 (0.22 - 0.63) |
| Willing to participate | 145 (73%) | 174 (90%) | 18.63 | 1 | <.01 | 2.72 (1.67 - 4.42) |
| No choice | Choice | |||||
| TRIAL 2 | questionnaire (n = 294) | interview or questionnaire (n = 298) | X 2 | df | p | RR (95%CI) |
| Participation rate | 134 (46%) | 177 (59%) | 11.33 | 1 | <.01 | 1.34 (1.13 - 1.59) |
| Conditional participation rate | 134 (53%) | 177 (66%) | 9.25 | 1 | <.01 | 1.39 (1.12 - 1.71) |
| Willing to participate | 253 (86%) | 268 (90%) | 2.11 | 1 | 0.146 | 1.39 (0.89 - 2.16) |
Abbreviations: X2 = chi square, RR = relative risk.