Nonresponse error in injury-risk surveys.

Background: Nonresponse is a potentially serious source of error in epidemiologic surveys concerned with injury control and risk. This study presents the findings of a records-matching approach to investigating the degree to which survey nonresponse may bias indicators of violence-related and unintentional injuries in a random-digit-dialed (RDD) telephone survey.

Methods: Data from a statewide RDD survey of 4155 individuals aged 16 years and older conducted in Illinois in 2003 were merged with ZIP code-level data from the 2000 Census. Using hierarchical linear models, ZIP code-level indicators were used to predict survey response propensity at the individual level. Additional models used the same ZIP code measures to predict a set of injury-risk indicators.

Results: Several ZIP code measures were found to be predictive of both response propensity and the likelihood of reporting partner violence. For example, people residing in high-income areas were less likely to participate in the survey and less likely to report forced sex by partner, processes that suggest an over-estimation of this form of violence. In contrast, estimates of partner isolation may be under-estimated, as those residing in geographic areas with smaller-sized housing were less likely to participate in the survey but more likely to report partner isolation. No ZIP code-level correlates of survey response propensity, however, were found also to be associated with driving-under-the-influence (DUI) indicators.

Conclusions: There is evidence of a linkage between survey response propensity and one variety of injury prevention measure (partner violence) but not another (DUI). The approach described in this paper provides an effective and inexpensive tool for evaluating nonresponse error in surveys of injury prevention and other health-related conditions.