Nonresponse bias in a general population survey of eating-disordered behaviour

Objective To investigate nonresponse bias in a two-phase epidemiologic study of eating-disordered behavior. Method Self-report questionnaires were delivered to a community sample of women aged 18-45 drawn from the electoral roll. Follow-up interviews were completed with a subgroup of respondents. Eating disorder psychopathology, general physical and mental health, and sociodemographic characteristics were compared among early (n = 259) and late (n = 71) respondents at the first phase of the study and among individuals with whom interviews were completed (n = 208) and individuals declining to be interviewed (n = 63) at the second phase. Results With respect to levels of eating disorder psychopathology, and on all other measures, individuals who responded at the first phase of the study only after repeated reminders did not differ from those who responded to the initial mailout, and individuals who declined to be interviewed did not differ from individuals with whom interviews were completed. Conclusions Nonresponse bias among individuals declining to be interviewed is unlikely to pose a problem in two-phase epidemiologic studies of eating disorders. Further research is needed to examine the characteristics of nonrespondents at the first phase of such studies