The paper outlines the methodological issues connected to national statistics, their cartographical representations, and the methods of conducting censuses. During the Paris Peace Conference representatives of new Central- and Eastern European states vehemently criticized the ethnic statistics developed by the empires, mostly Russian and Austro-Hungarian. The censuses, conducted in these new states in early 1920s, were criticized along similar lines by the minorities. Among the most vociferous critics were German geographers. Pointing out to the results of the plebiscites in Silesia, Carinthia and other regions they argued, that national identity did not have to correspond to the mother tongue, and census authorities should have taken it into account. Paradoxically, they considered this point valid only to the Central and Eastern Europe, not Western Europe. In the final part of the paper the position of geographers and statisticians in post-war debates are confronted with information on the behaviour of respondents during the censuses in Poland and Czechoslovakia.