“…In this case, the multivariate vector of dependent variables Yi (5) is characterized by the following variables:Y1 = βCu, Y2 = ϑCu Y3 = εCu, Y4 = ηCu. However, in the analysis, the vectors of mean values of the variables i (6), where i=1, 2, …, N for different systems of factors and their levels (6) were compared [Stanisz, 2007;Niedoba, 2013;Niedoba et al, 2016a, Niedoba et al, 2016b. The relevance of the main effects among the investigated factors was considered for significance level equalled to 95%, which means that the model with a P-value lower than 0.05 could be considered.…”