Muenchen, Robert A (Bob)
2007-Nov-20 14:03 UTC
[R] p.adjust on matrix of P-values from correlations
Hi All, I'm stumped on something that must be trivial. I created a correlation matrix on 4 variables (6 correlations) using Hmisc's rcorr function. I wanted to correct the P-value matrix for the number of tests done, so I ran it through the p.adjust function. That function adjusted for the 12 p-values it saw, rather than 6. I added the argument n=6 to p.adjust but it requires that n be greater than the length of x. I guess its author assumed you would always be correcting for more tests than it could see. I changed the matrix into a long vector to see if that would matter. The help file says it requires vector, but the result was the same. If I were using the conservative Bonferroni correction, I could divide the corrected P-values by 2 to make n=6 after the fact. However, I'm using Holm's sequential method, so that's no good. Any ideas? Thanks, Bob P.S. I'm using R 2.6.0 Patched on Windows XP. ========================================================Bob Muenchen (pronounced Min'-chen), Manager, Statistical Consulting Center U of TN Office of Information Technology Stokely Management Center, Suite 200 916 Volunteer Blvd., Knoxville, TN 37996-0520 Voice: (865) 974-5230 FAX: (865) 974-4810 Email: muenchen at utk.edu Web: http://oit.utk.edu/scc Map: http://www.utk.edu/maps News: http://listserv.utk.edu/archives/statnews.html =========================================================