This paper examines some essential characteristics of bibliometric data of the type analysed by Lotka. It will be shown that most bibliometric data have peculiar characteristics, which makc most statistical measures change systematica11y according to the change of sample size, even when the population is identical. Because of this, it is particulary difficult to establish a proper framework of interpretation for bibliometric phenomena on the basis of bibliometric samples. Two possible ways of estab1ishing frameworks of interpretation are suggested, i. e. to pay attention to samp1ing stages and to use the statistical analysis that can take into account pecu1iarities of bib1iometric data.