PEARSON'S OR SPEARMAN'S CORRELATION COEFFICIENT - WHICH ONE TO USE?

Mosf commonly used correlation coefficients are Pearson's product moment correlation coefficient and Spearman's rank correlation coefficient. The aim of this paper is to compare a Pearson's and Spearman's coefficient of correlation on the same data set. The winter wheat grain cadmium (Cd) concentration was correlated to grain zinc (Zn) concentration, plant height, plant weight, number of spikelets per spike and 1000 kernel weight. Data were collected from the experiment carried out in semi controlled conditions, where genotypic specificity of winter wheat varieties was tested on the grain Cd and Zn accumulation on uncontaminated and Cd contaminated soil. Results showed that selection of most convenient correlation coefficient mostly depends on the type of variables, presence of outliers normality and linearity of relationship