Use of Covariates and Survey Wave to Adjust for Nonresponse

Abstract Using covariates available on all sampled individuals along with an intensive follow‐up of nonrespondents is a useful approach to reduce the impact of nonresponse. We examined the performance of several different nonresponse models to account for such covariates and multiple survey waves to estimate the prevalence of birth control use in 106463 women taking the teratogenic drug Accutane. Nonrespondents to a first mailing were followed with two more mailings and then a telephone call. The first mailing had a response rate of 59.7 percent; the overall nonresponse rate was 15.2 percent. Age was available on all women and was strongly associated with both response and birth control use. We considered both multiple imputation and weighting strategies using information on age and time to response assuming that nonrespondents were: (i) like all respondents conditional on age, (ii) like reluctant respondents conditional on age, and (iii) projected from a model which includes trend. Simulation studies were used to examine the potential bias in this setting and we compared models under different assumptions about the missing data mechanism. Results describe the extent to which availability of covariate information and use of multiple waves improves estimation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)