A comparative study of correlation coefficients in spatially MRSI-observed neurochemicals from multiple sclerosis patients

In measuring the association between magnetic resonance spectroscopic imaging (MRSI)-observed neurochemicals from multiple sclerosis (MS) patients, the classic correlation coefficients such as the Pearson's r, Spearman's A and Kendall's F do not take into account the spatial dependence of the observations. This paper reports a comparative study on these classic correlation coefficients (Pearson's r, Spearman's A and Kendall's F ) and some more recent correlation coefficients (Tjostheim's a, the modified t) that take into account the spatial dependence of the intensities of the concentrations of several neurochemicals in MS patients. Our study indicates that the use of the classic correlation coefficients that ignores the spatial dependence of the observations may overestimate the statistical significance of the results.