Abstract
In 1986 the Japanese Ministry of Health and Welfare carried out the Comprehensive Survey of Living Condition of the People on Health and Welfare which included the Survey on Household Questionnaire and the Survey on Income Questionnaire. The former was done for 4966 survey units (about 240 thousands households) drawn from 750 thousands survey units in the National Census. Among these, 940 survey units (about 40 thousands households) were drawn and the latter survey was carried out. In the statistics the mean of household incomes was estimated only on the basis of the information obtained from the Survey on Incomes Questionnaire. However, some items in the questionnaire of the Survey on Households Questionnaire must have correlation with the mean of household incomes. Hence the precision of the estimation may be improved by using the information obtained from the Survey on Households Questionnaire, whose scale was five times larger than that of the Survey on Incomes Questionnaire.
In this study we propose four schemes which improve the precision of estimating the mean of household incomes classified by the areas and age-classes of householders. We then make some investigation and comparison of these schemes together with the traditionally used scheme. In the analysis we assume a regression model where the objective variable y is a household income and the explanatory variables' vector x is corresponding to the questionnaire of the Survey on Households.
