Wouter, > what is the best way to do an ANOVA on two-factor experiments with > repeated measures on one of the factors (e.g. time) in R, (with > Greenhouse-Geisser Epsilon or Huynh-Feldt Epsilon calculation, if
You could use aov() with an Error term on your subjects factor; this follows the classical "split-plot" approach. But I do not believe you will find any existing R code to do the G-G or H-F corrections. And I doubt there ever will be, because the better strategy is to use linear mixed-effect modeling approaches. See for example, Diggle et al (Analysis of Longitudinal Data, 2001); Pinheiro & Bates (Mixed Effects Model with S, 2000); and Venables & Ripley (MASS 4th edition, Sitka Trees example.) You get the split-plot approach with a uniform correlation (also called compound symmetry) specification for your error matrix, but other alternatives are available. If your repeated measure is time, my experience (with biology data) finds that a first order autoregression or something similar is better. The correlation between timepoint pairs weakens as the distance between them increases. Hope that helps. Best Regards, Bill ---------------------------------------- Bill Pikounis, Ph.D. Biometrics Research Department Merck Research Laboratories PO Box 2000, MailDrop RY33-300 126 E. Lincoln Avenue Rahway, New Jersey 07065-0900 USA [EMAIL PROTECTED] Phone: 732 594 3913 Fax: 732 594 1565 > -----Original Message----- > From: wouter buytaert [mailto:[EMAIL PROTECTED] > Sent: Friday, July 18, 2003 6:34 AM > To: [EMAIL PROTECTED] > Subject: [R] repeated measures anova > > > Hello, > > what is the best way to do an ANOVA on two-factor experiments with > repeated measures on one of the factors (e.g. time) in R, (with > Greenhouse-Geisser Epsilon or Huynh-Feldt Epsilon calculation, if > possible (as described in Ott and Longnecker, 2001. > Statistical Methods > and Data Analysis 5th ed., chapter 18)) > > Thanks, > > Wouter > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > ------------------------------------------------------------------------------ Notice: This e-mail message, together with any attachments, ...{{dropped}} ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
