18.4 - Example - Correlation Coefficients

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SAS Example (19.1_correlation.sas): Age and percentage body fat were measured in 18 adults. SAS PROC CORR provides estimates of the Pearson, Spearman, and Kendall correlation coefficients. It also calculates Fisher's Z transformation for the Pearson and Spearman correlation coefficients in order to get 95% confidence intervals.

SAS Program 19.1

The resulting estimates for this example are 0.7921, 0.7539, and 0.5762, respectively for the Pearson, Spearman, and Kendall correlation coefficients. The Kendall tau-b correlation typically is smaller in magnitude than the Pearson and Spearman correlation coefficients.

The 95% confidence intervals are (0.5161, 0.9191) and (0.4429, 0.9029), respectively for the Pearson and Spearman correlation coefficients. Because the Kendall correlation typically is applied to binary or ordinal data, its 95% confidence interval can be calculated via SAS PROC FREQ (this is not shown in the SAS program above).