From: A systematic review of the effect of retention methods in population-based cohort studies
 |  | Data Collection Method | ||
---|---|---|---|---|
 | Postal | Face-to-Face | Telephone | Mixed |
Evaluated Retention Method, reference number | Average increase in retention rate, proportion (95% CI) | Average increase in retention rate, proportion (95% CI) | Average increase in retention rate, proportion (95% CI) | Average increase in retention rate, proportion (95% CI) |
Incentives | Â | Â | Â | Â |
RCT - Financial Only | Â | Â | Â | Â |
Doody[22]* | 0.01 (0.01, 0.01) | Â | Â | Â |
 |  |  | 0.05 (0.05, 0.06) | |
 |  |  | 0.02 (0.02, 0.03) | |
 | 0.85 (0.84, 0.85) |  |  | |
Rodgers[32]*** | Â | Â | 0.80 (0.87, 0.88) | Â |
RCT - Gift Only | Â | Â | Â | Â |
Kalsbeek[23]*** | Â | Â | 0.78 (0.76, 0.79) | Â |
White[33]* | 0.11 (0.01, 0.14) | Â | Â | Â |
RCT - Mixed | Â | Â | Â | Â |
 | 0.28 (0.27, 0.29) |  |  | |
Non-RCT - Gift Only | Â | Â | Â | Â |
Hoffman[40] | 0.47 (0.44, 0.49) | Â | Â | Â |
Non-RCT - Mixed | Â | Â | Â | Â |
Rudy [45]*** | 0.72 (0.65, 0.79) | Â | Â | Â |
Reminder Letters | Â | Â | Â | Â |
1 Letter Posted | Â | Â | Â | Â |
Boys[34] | 0.12 (0.10, 0.15) | Â | Â | Â |
Hoffman[40] | 0.02 (0.02, 0.03) | Â | Â | Â |
Koo[24]** | 0.32 (0.29, 0.36) | Â | Â | Â |
Russell[46] | 0.03 (0.03, 0.03) | Â | Â | Â |
2 Letters Posted | Â | Â | Â | Â |
Clarke[36] | 0.18 (0.15, 0.22) | Â | Â | Â |
Eagan[37] | 0.18 (0.17, 0.19) | Â | Â | Â |
Walker[49] | 0.18 (0.17, 0.19) | Â | Â | Â |
0.03 (0.03, 0.03) | Â | Â | Â | |
0.10 (0.10, 0.11) | Â | Â | Â | |
0.46 (0.45, 0.47) | Â | Â | Â | |
3 Letters Posted | Â | Â | Â | Â |
Ullman[48] | 0.23 (0.20, 0.26) | Â | Â | Â |