Francis J. Flanagan 1956 The rank correlation coefficient, r_s, which involves less computation than the product moment correlation coefficient, r, can be used to indicate the degree of relationship between two elements. The methods is applicable in situations where the assumptions underlying distribution correlation theory may not be satisfied. Semiquantitative spectrographic analyses can be used to calculate rank correlations between elements because the results are already partly ranked in an analytical report. application/pdf 10.3133/tei628 en U.S. Geological Survey Semiquantitative spectrographic analysis and rank correlation in geochemistry reports