Principal component analysis (PCA) for the chemical composition of groundbaits intended for bream, carp, and roach, taking into account the content of C, N, P, protein, Hg, Cd, Pb, and As. Red circle: confidence limit (95%) for identification of outlier samples; Red lines: principal component axes (Factor 1 and Factor 2), center of the coordinate system; Blue vectors: variable loadings, showing how strongly and in what direction individual variables influence the main components of PCA.