Impact of correcting for nonresponse by weighting on estimates of alcohol consumption

This study describes the characteristics of nonrespondents and assesses the impact of unit nonresponse on estimates of central alcohol consumption variables by examining the impact of corrective weighting.

The data came from a Finnish general population random sample of 1,932 respondents (987 women) (response rate: 78.1%). The survey was carried out in the year 2000 using face-to-face interviews. The impact of unit nonresponse was assessed by comparing results using (1) no weighting; (2) poststratified weights adjusted for age, gender and region; (3) weights obtained from a statistical model predicting response propensity; and (4) weights from the model, adjusted to match the population distribution for age, gender and region. Extensive auxiliary information used to predict response propensity came from administrative registers.

Compared with respondents, both male and female nonrespondents had fewer children, lived in urban areas and lived in southern Finland. Male nonrespondents were also older; female nonrespondents more often had only a basic education and were less often in the second-highest income quartile. The change in alcohol variables resulting from the adjustment for nonresponse was small, however, and the difference between the different weighting schemes was even smaller.

If nonrespondents' drinking differs considerably from that of respondents, this difference cannot be captured even by using extensive auxiliary information and an elaborate model predicting propensity of nonresponse.