In our paper we focus on the economic situation of Polish families observed in the consecutive waves of the household budget data collected by the Central Statistical Office within the period of 1987 - 1993. The available data put various limits on our investigation. It is a common sense that in all turbulent economic systems a substantial part of GNP (estimated sometimes up to 20 or 30 %) exists beyond the scope of the official statistics. Incomes were under reported on a significant scale under the old economic regime but distributional effects of the under-reporting have probably changed. Another deficit of the Polish household budget surveys is a limited coverage of the total population. Up to 1993 Polish households were stratified by the sampling procedure in four socio-economic group: workers (employees), farmers, mixed households (households receiving incomes from farm and employment) and pensioners. In the consequence, households with heads being a self-employed person in the private non-agricultural sector (and few other categories of minor importance) were excluded from the surveys. The excluded groups add up to approximately 12 % of population in the end of 80's. The re-weighting procedure we use in our investigations cannot set off a total bias caused by the incorrect sample procedure.