Retaining young people in longitudinal surveys: Rewarding postal survey participation improves response rates
posted on: Mar 19, 2010
Research conducted by the MRC/CSO Social and Public Health Sciences Unit found that rewarding postal survey participation improves response rates and helps retain young people over time. Offering a definite reward for participation (£10 voucher sent on receipt of their completed questionnaire) was the only incentive that had a significant and beneficial impact on participation.
As part of a trial to evaluate teacher-delivered sex education (SHARE study), Dr Marion Henderson led a study to establish the effectiveness of different incentives for participation. The trial surveyed 8,430 young people every two years from age 14 to age 20 about their sexual attitudes, knowledge and behaviour. At age 14 and 16 the majority of the young people were surveyed in their school classrooms and participation was high. However, participation became a concern when the young people left school and were sent postal surveys. To learn the best way to improve and retain participation, the impact of four different incentives on participation was explored. Respondents were randomly allocated to four different kinds of incentive: 1) no incentive; 2) chance of winning one of twenty-five vouchers worth £20; 3) chance of winning one £500 voucher; and 4) a definite reward of a £10 voucher sent on receipt of their completed questionnaire. The impact of these incentives on participation was explored when the young people had left school and were aged 18 and 20.
The only incentive that had a significant and beneficial impact for young people was to offer a definite reward for participation (£10 voucher sent on receipt of their completed questionnaire). Forty-one percent of the young people offered this definite reward participated at age 18 versus 27% or less from the other incentives explored. Similarly, 35% of the group offered a definite reward participated at age 20 versus 25% or less for the other groups.
Dr Marion Henderson commented: "There is an increasing trend towards lower participation in questionnaire surveys. This reduces representativeness, increases costs and introduces particular challenges to longitudinal surveys, as researchers have to use complex statistical techniques which attempt to address attrition. We have learned that the best strategy for retaining all groups of young people and one that improved retention at both age 18 and age 20 was to offer a definite reward for participation. This is expensive: however, given the many benefits of retaining a longitudinal sample, we recommend inclusion of this as a research cost for cohort and other repeat-contact studies."
The findings are published in BMC Medical Research Methodology.