Re: [Rd] Orthogonal polynomial ANOVA or polynomial regression?

From: peter dalgaard <pdalgd_at_gmail.com>
Date: Thu, 24 Mar 2011 17:09:45 +0100

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

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