Not that I doubt you Karl (you seem very educated on statistical issues) but all the textbooks I have used talk about HSD as a post hoc test that is only appropriate to use after finding significance with an ANOVA. Do you have something I could reference to support this? The other thing is if HSD is a replacement for ANOVA it seems even more unusual that they would come to different conclusions. Thanks, Rick Dr. Rick Froman Psychology Department Box 3055 John Brown University Siloam Springs, AR 72761 (479) 524-7295 [EMAIL PROTECTED] "Pete, it's a fool that looks for logic in the chambers of the human heart" - Ulysses Everett McGill
________________________________ From: Wuensch, Karl L [mailto:[EMAIL PROTECTED] Sent: Tue 4/3/2007 6:18 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] ANOVA, HSD, and LSD I wouldn't, because Tukey's HSD was designed as a REPLACEMENT for the ANOVA, not as something to do after an ANOVA. Frankly, there is not often any good reason to do an ANOVA other than that everybody else does it and it is expected. Better off to make a set of focused contrasts that address the research questions you want to answer. If you just must make pairwise contrasts, use the REGWQ instead of the HSD -- it has more power and holds familywise alpha at no more than its nominal level. If you have only three groups, use Fisher's procedure, which, by the way, is the only one of the commonly employed pairwise procedures which requires that you do an ANOVA first (and that the ANOVA be significant). With only three groups it holds familywise error at the nominal level. Although pooled error is commonly employed with Fisher's procedure, one should use individual error terms if heterogeneity of variance is evident. Cheers, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Karl L. Wuensch, Chair, Faculty Information Technology Review Committee East Carolina University, Greenville NC 27858-4353, USA, Earth Voice: 252-328-9420 Fax: 252-328-6283 [EMAIL PROTECTED] http://core.ecu.edu/psyc/wuenschk/klw.htm -----Original Message----- From: Rick Froman [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 03, 2007 2:50 PM To: Teaching in the Psychological Sciences (TIPS) Subject: [tips] ANOVA interpretation How would you interpret an ANOVA result where the F-test was significant but none of the multiple comparisons were significant in an HSD comparison? Rick Dr. Rick Froman, Chair Division of Humanities and Social Sciences Professor of Psychology John Brown University 2000 W. University Siloam Springs, AR 72761 [EMAIL PROTECTED] (479) 524-7295 http://www.jbu.edu/academics/hss/faculty/rfroman.asp "Pete, it's a fool that looks for logic in the chambers of the human heart." - Ulysses Everett McGill --- To make changes to your subscription go to: http://acsun.frostburg.edu/cgi-bin/lyris.pl?enter=tips&text_mode=0&lang= <http://acsun.frostburg.edu/cgi-bin/lyris.pl?enter=tips&text_mode=0<=> english --- To make changes to your subscription go to: http://acsun.frostburg.edu/cgi-bin/lyris.pl?enter=tips&text_mode=0&lang=english <http://acsun.frostburg.edu/cgi-bin/lyris.pl?enter=tips&text_mode=0<=english>
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