EN
The article presents a selection of statistical research methods that can be applied in comparisons of series of numerical variables that describe selected social phenomena. The presentation of methods is base on the example of analysis of relations between selected socio-economic parameters and the ethnic diversity in Black African countries. On the first stage of analysis the most important features characterising selected phenomena have been chosen. In order to get the quantitative description of the phenomena, for the purpose of their statistical analysis, such measures as the indicator of socio-ethnic coherence and the synthetic human development index were applied. The initial hypothesis have been verified applying the rank differential calculus - groups of countries have been selected according to the grade in which the hypothesis has been verified. Pearson's correlation coefficient has been used to verify the rank method. As each pair of analysed phenomena is complex, many comparisons are possible. Therefore the selection of the most relevant features characterising the studied phenomena and the selection of reliable research methods seems to be the most important elements of analysis.