Hello Using R 2.2.1 on a Windows machine. Has anyone programmed the Welch test for equality of variances? I tried RSiteSearch, but this gave references to t test and oneway.test, which are not quite what I need.....I need the Welch test itself, for use in a meta-analysis (to determine if variances are equal). TIA Peter Peter L. Flom, PhD Assistant Director, Statistics and Data Analysis Core Center for Drug Use and HIV Research National Development and Research Institutes 71 W. 23rd St http://cduhr.ndri.org www.peterflom.com New York, NY 10010 (212) 845-4485 (voice) (917) 438-0894 (fax)
?t.test t.test has a var.equal option that you can set to FALSE to use the Welch approximation. -Christos -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Peter Flom Sent: Tuesday, March 28, 2006 4:41 PM To: r-help at r-project.org Subject: [R] Welch test for equality of variance Hello Using R 2.2.1 on a Windows machine. Has anyone programmed the Welch test for equality of variances? I tried RSiteSearch, but this gave references to t test and oneway.test, which are not quite what I need.....I need the Welch test itself, for use in a meta-analysis (to determine if variances are equal). TIA Peter Peter L. Flom, PhD Assistant Director, Statistics and Data Analysis Core Center for Drug Use and HIV Research National Development and Research Institutes 71 W. 23rd St http://cduhr.ndri.org www.peterflom.com New York, NY 10010 (212) 845-4485 (voice) (917) 438-0894 (fax) ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Peter, I don't know the Welch test for variances, but you might consider using the Fligner-Killeen test (fligner.test) or one of the Levene test variations (package:car). A useful reference is WJ Conover, ME Johnson, MM Johnson. 1981. Technometrics 23:351 with a minor correction in Technometrics 26:302. Peter Ehlers Peter Flom wrote:> Hello > > Using R 2.2.1 on a Windows machine. > > Has anyone programmed the Welch test for equality of variances? > > I tried RSiteSearch, but this gave references to t test and > oneway.test, which are not quite what I need.....I need the Welch test > itself, for use in a meta-analysis (to determine if variances are > equal). > > > TIA > > Peter > > > > Peter L. Flom, PhD > Assistant Director, Statistics and Data Analysis Core > Center for Drug Use and HIV Research > National Development and Research Institutes > 71 W. 23rd St > http://cduhr.ndri.org > www.peterflom.com > New York, NY 10010 > (212) 845-4485 (voice) > (917) 438-0894 (fax) > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html-- Department of Mathematics and Statistics University of Calgary, 2500 University Dr. NW ph: 403-220-3936 Calgary, Alberta T2N 1N4, CANADA fax: 403-282-5150