Non-response behaviour in the Bank of Italy�s Survey of Household Income and Wealth

This paper aims to describe non-respondents in the Bank of Italy�s Survey of Household Income and Wealth (SHIW) and to measure the underestimation of income and wealth attributable to non-response. The evidence confirms that non-response is not random, since it is more frequent among wealthier households. Therefore exclusive use of poststratification procedures based on demographic characteristics only, which are commonly employed, cannot properly adjust for the selection process observed in the SHIW. As to the estimates of average aggregates, the bias seems to be greater for financial assets (the adjusted estimates are from 15 to 31 per cent higher than the unadjusted) than for income (for which the adjustments vary from 5 to 14 per cent, probably owing to a greater asymmetry in the distribution of wealth.