Clinical chemistry
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Comparative Study
Comparison of product moment and rank correlation coefficients in the assessment of laboratory method-comparison data.
We have studied the effects of range and distribution of data on product moment and rank correlation coefficients when deviation from a linear relationship was due solely to experimentally produced random error. All correlation coefficients (Pearson r, Spearman rho, and Kendall tau) were markedly influenced by the range of the data, and, for the rank correlation coefficients, the effect of range varied for different data distributions. ⋯ Thus, neither product moment nor rank correlation coefficients are of value in analysis of laboraoty method-comparison data. The standard deviation of the residual error of regression should be calculated as a measure of the random error about the regression line.