Description: There were received the coverage factors of the variates compositions which were arcsine distributed. The research was made for big and small number of measuring results. The attention was paid to existing correlation between these results too. There were received the following functional dependences: a coverage factor vs. mean square deviation of results were researched, a coverage factor vs. correlation coefficient of results were researched. The errors were researched which were arise from ignoring a correlation factor between measuring results.