A systematic review of the effect of retention methods in population-based cohort studies

BMC Public Health

Table 3 Increase in Study Retention Rates for Repeat Questionnaires and Alternative Methods of Data Collection by Data Collection Type

		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)
Repeat Questionnaires
2 Questionniares Posted
Doody[22]*	0.08 (0.08, 0.08)
Eagan[37]	0.18 (0.17, 0.19)
Hoffman[40]	0.05 (0.04, 0.06)
Rimm[31]	0.16 (0.16, 0.17)
Ullman[48]	0.04 (0.03, 0.06)
3 Questionniares Posted
Clarke[36]	0.18 (0.15, 0.22)
White[33]*	0.06 (0.04, 0.08)
6 Questionnaires Posted
Calle[35]	0.37 (0.37, 0.38)
Russell[46]	0.23 (0.23, 0.23)
Alternative Methods of Data Collection
Postal Questionnaires
Garcia[38]			0.01 (0.01, 0.02)
Mills[43]		0.17 (0.15, 0.19)
Face-to-Face Interviews
Lissner[41]		0.18 (0.16, 0.21)
Tolus so[47]			0.02 (0.02, 0.02)
Telephone Interviews
Boys[34]	0.01 (0.01, 0.03)
Calle[35]	0.02 (0.02, 0.02)
Michaud[42]	0.17 (0.16, 0.18)
Russell[46]	0.02 (0.02, 0.02)
WHA Research Group (YC)[50–53]	0.01 (0.01, 0.01)
WHA Research Group (MC)[50–53]	0.05 (0.05, 0.05)
WHA Research Group (OC)[50–53]	0.08 (0.08, 0.09)
Mixed (Postal, Telephone & Face-to-Face) Novo[44]		0.42 (0.39, 0.44)

ISSN: 1471-2458