Secular trends in underreporting of cigarette consumption.

Information on the cigarette smoking habits of all New Zealanders aged 15 years and over was collected in two consecutive national censuses in 1976 and 1981. These data show that the self-reported per capita consumption of cigarettes declined by 9.4 per cent during this five-year period. A comparison of census data with national cigarette sales data for the corresponding years indicated considerable underreporting of cigarette use in the two censuses. However, there was little change in the degree of underreporting between 1976 (28 per cent) and 1981 (30 per cent) and the estimated decline in per capita consumption of cigarettes based on sales data (8.6 per cent) was similar to the census-based estimate. These findings suggest that trends in self-reported consumption are a reliable indicator of national trends in cigarette smoking habits.