Non-Sampling Errors in Household Surveys: The Bank of Italy’s Experience

Non-sampling errors are a serious problem in household surveys. This paper exploits the Bank of Italy’s Survey on Household Income and Wealth to show how these issues can be studied and how the main effects on estimates can be accounted for. The topics examined are unit non-response, uncorrelated measurement errors and some specific cases of underreporting. The unit non-response can be overcome by weighting valid cases using external (typically demographic and geographical) information or by modelling the respondents’ propensities to participate in the survey. The effect of the uncorrelated measurement errors can be evaluated using specific reliability indices constructed with the information collected over the panel component. The underreporting bias of income and wealth is estimated by combining statistical matching techniques with auxiliary information and by exploiting different response behaviours across different groups.