[R] in cor.test, difference between exact=FALSE and exact=NULL

Andrew Yee andrewjyee at gmail.com
Fri Aug 24 00:41:14 CEST 2007

Pardon my ignorance, but is there a difference in cor.test between
exact=FALSE and exact=NULL when method=spearman?

Take for example:

cor.test(x,y, method="spearman", exact=NULL)

This gives an error message,
Warning message:  Cannot compute exact p-values with ties in:
cor.test.default(x, y, method = "spearman", exact = NULL)

However, when exact is changed to FALSE, this seems to run okay.

cor.test(x,y, method="spearman", exact=FALSE)

Question:  should this be exact = FALSE in the documentation and/or the code?

MGH Cancer Center

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