Examining non-response bias in substance use research--are late respondents proxies for non-respondents?

Drug Alcohol Depend. 2013 Sep 1;132(1-2):316-23. doi: 10.1016/j.drugalcdep.2013.02.029. Epub 2013 Mar 25.


Background: Non-response is a major concern among substance use epidemiologists. When differences exist between respondents and non-respondents, survey estimates may be biased. Therefore, researchers have developed time-consuming strategies to convert non-respondents to respondents. The present study examines whether late respondents (converted former non-participants) differ from early respondents, non-consenters or silent refusers (consent givers but non-participants) in a cohort study, and whether non-response bias can be reduced by converting former non-respondents.

Methods: 6099 French- and 5720 German-speaking Swiss 20-year-old males (more than 94% of the source population) completed a short questionnaire on substance use outcomes and socio-demographics, independent of any further participation in a cohort study. Early respondents were those participating in the cohort study after standard recruitment procedures. Late respondents were non-respondents that were converted through individual encouraging telephone contact. Early respondents, non-consenters and silent refusers were compared to late respondents using logistic regressions. Relative non-response biases for early respondents only, for respondents only (early and late) and for consenters (respondents and silent refusers) were also computed.

Results: Late respondents showed generally higher patterns of substance use than did early respondents, but lower patterns than did non-consenters and silent refusers. Converting initial non-respondents to respondents reduced the non-response bias, which might be further reduced if silent refusers were converted to respondents.

Conclusion: Efforts to convert refusers are effective in reducing non-response bias. However, converted late respondents cannot be seen as proxies of non-respondents, and are at best only indicative of existing response bias due to persistent non-respondents.

Keywords: Early respondent; Later respondent; Non-response bias; Substance use; Young men.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Drinking / psychology
  • Algorithms
  • Bias*
  • Cohort Studies
  • Data Collection
  • Educational Status
  • Epidemiologic Research Design*
  • France
  • Germany
  • Humans
  • Logistic Models
  • Male
  • Marijuana Smoking / psychology
  • Prevalence
  • Risk Factors
  • Socioeconomic Factors
  • Substance-Related Disorders / psychology*
  • Tobacco Use / psychology
  • Urban Population
  • Young Adult