title: The effect of reminders in a web-based intervention study.
abstract: Knowledge on effective strategies to encourage participation in epidemiological web-based research is scant. We studied the effects of reminders on overall participation. 3,876 employees were e-mailed a baseline web-based lifestyle questionnaire. Nine months later, a follow-up questionnaire was sent. To encourage study participation, 4-5 and 11 e-mail reminders were sent at baseline and follow-up, respectively. Additional reminders (media articles, flyers, SMS etc) were also administered. Reminders (e-mails + additional) were given in low (≤ 6 reminders), medium (7-9 reminders) or high amounts (>9 reminders). Participation was examined with respect to participant characteristics (i.e. age, sex, Body Mass Index, occupation), type/number of reminders, and time of participation. Most participants were males, 35-49 years, and field workers (non-office based). About 29 % responded before any e-mail reminder, following 26 and 45 % after 1 respective ≥ 2 e-mail reminders. Participant characteristics were not related to when the participants responded. The 4-5 e-mail reminders increased total response rate by 15 %, the eleven by 21 % (greatest increases in September). Those receiving medium amounts of reminders (reference) had the highest response rate (75 %), likewise office workers (54 %) compared to field workers (33 %). High amounts of reminders were particularly effective on office workers. The participants' characteristics were not related to when they responded in this web-based study. Frequent reminders were effective on response rates, especially for those with high Internet availability. The highest increases in response rates were found in September.
authors.affiliation: Unit of Clinical Epidemiology, T2, Department of Medicine, Karolinska Institutet, 171 76 Stockholm, Sweden. Madeleine.Svensson@ki.se
authors.forename: Madeleine
authors.initials: M
authors.lastname: Svensson
authors.forename: Tobias
authors.initials: T
authors.lastname: Svensson
authors.forename: Andreas Wolff
authors.initials: AW
authors.lastname: Hansen
authors.forename: Ylva
authors.initials: Y
authors.lastname: Trolle Lagerros
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D034742:Electronic Mail; D005260:Female; D005500:Follow-Up Studies; D015438:Health Behavior; D006293:Health Promotion; D006306:Health Surveys / Q000379:methods*; D006801:Humans; D020407:Internet; D008019:Life Style; D008297:Male; D008875:Middle Aged; D016272:Occupational Health; D011890:Railroads; D017010:Reminder Systems; D011795:Surveys and Questionnaires; D013548:Sweden; D055815:Young Adult