A comparison of participants with non-participants in a population-based epidemiologic study: the Melbourne Visual Impairment Project

Ophthalmic Epidemiol. 1997 Jun;4(2):73-81. doi: 10.3109/09286589709057099.


Purpose: Adequate participation in population-based studies in essential to ensure that the sample is representative of the population under investigation. Participants may differ from non-participants on important variables such as age, sex socioeconomic status, and general health factors. The Melbourne Visual Impairment Project (Melbourne VIP) is a population-based study designed to increase understanding of the prevalence and severity of common ocular disorders affecting people 40 years of age and over.

Aim: The aim of this study was to determine the potential for any non-response bias by comparing data from participants and non-participants of the Melbourne VIP.

Methods: Specific demographic and general variables were compared between the two groups. The variables included age, sex, education level, and social status. The reason for non-attendance was also recorded.

Results: A total of 3271 (83%) eligible residents from the 9 sample areas were screened; 46% males and 54% females. Language spoken at home was significantly associated with participation. Residents whose main language at home was not English were less likely to attend the screening centre. (OR: 0.60; CI: 0.44-0.81). The main reasons given for non-attendance by eligible residents were lack of interest (6%), too busy to attend (4%), personal illness (2%), and attend own eye specialist (2%).

Conclusion: We believe these results will not impact significantly on the interpretation of gender and age-specific data from the Melbourne VIP.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Australia / epidemiology
  • Bias
  • Data Interpretation, Statistical
  • Female
  • Humans
  • Incidence
  • Life Style
  • Male
  • Middle Aged
  • Patient Participation* / statistics & numerical data
  • Prevalence
  • Retrospective Studies
  • Social Class
  • Vision Disorders / diagnosis
  • Vision Disorders / epidemiology*