Diverse recruitment strategies result in different participation percentages in a web-based study, but in similar compliance
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We compared participation and compliance with a web-based data collection on infections among population-based samples recruited in different ways.
Individuals were recruited from participants in the German National Cohort study (Group A, n = 279) or persons who were invited to this study but did not participate (Group B, n = 53). A third group was invited to the web-based study only (Group C, n = 145).
Response varied among groups between 3 % (B), 11 % (C) and 61 % (A), but compliance was similar (81–85 %). Response did not differ by age and sex. Compliance was lower among the youngest and oldest participants. In addition, participants currently not employed were more likely to have better compliance. Semi-parametric group-based modelling identified three distinct compliance trajectories; “poor compliance” (8 %), “improving compliance” (14 %) and “very good compliance” (78 %).
Participation differed among modes of recruitment, but compliance was similar among groups and notably high. Different recruitment approaches can be used and collected data can be combined to achieve greater sample sizes for longitudinal web-based studies.
KeywordsResponse Compliance Recruitment strategies Longitudinal study Non-responders Population-based study Second-stage non-response Web-based study German National Cohort
This project was conducted in the context of the Pretest studies (Pretest 2) of the German National Cohort (http://www.nationale-kohorte.de). These were funded by the Federal Ministry of Education and Research (BMBF), project number 01ER1203, and supported by the Helmholtz Association as well as by the participating universities and Institutes of the Leibniz Association. We also gratefully acknowledge the contribution to data collection by the study personnel in Hamburg, Hannover and Bremen.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The study was approved by the Ethics Committees of the State Boards of Physicians of the German Federal States of Bremen, Hamburg, and Lower Saxony. All subjects gave written informed consent before entering the study.