This publication inaugurates a series of analytical studies on foreign trade, the aim of which is to present recipients of statistical data the specificity of phenomena related to conducting statistical surveys in this area. The first study, which we are pleased to present to you, is devoted to the causes of discrepancies that can be observed for data on imports and exports in the aspect of international comparisons. In the publication you will find a description of the basic factors affecting the differences in the data presented in the scope of trade in goods, which are illustrated by specific examples regarding exchange with individual countries. A comparative analysis is the basis for presenting such phenomena as asymmetry, mirror statistic. In addition, the publication has been enriched with numerous charts and definitions of terms that can facilitate the analysis of the presented phenomena.