Dominick Samperi
2011-Mar-24 15:53 UTC
[Rd] Orthogonal polynomial ANOVA or polynomial regression?
Hi, I have not been able to find R tools that permit an orthogonal polynomial ANOVA analysis: single degree of freedom F-test comparisons including L, Q, C, etc. terms. Do such tools exist? I guess you can accomplish something similar by doing straightforward polynomial regression and removing powers manually, combined with ANOVA model comparisons. Thanks, Dominick
peter dalgaard
2011-Mar-24 16:09 UTC
[Rd] Orthogonal polynomial ANOVA or polynomial regression?
On Mar 24, 2011, at 16:53 , Dominick Samperi wrote:> Hi, > > I have not been able to find R tools that permit an orthogonal polynomial > ANOVA analysis: single degree of freedom F-test comparisons including > L, Q, C, etc. terms. Do such tools exist? > > I guess you can accomplish something similar by doing straightforward > polynomial regression and removing powers manually, combined with > ANOVA model comparisons.(Why R-devel? This is a plain R-help thing.) Look up contr.poly(), and poly(). Notice that for unbalanced designs, you still need to remove terms one at a time. -- Peter Dalgaard Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com