From pdalgd at gmail.com  Thu Mar 24 17:09:45 2011
From: pdalgd at gmail.com (peter dalgaard)
Date: Thu, 24 Mar 2011 17:09:45 +0100
Subject: [Rd] Orthogonal polynomial ANOVA or polynomial regression?
In-Reply-To: <AANLkTik09f7cr7hz+fLTe6BRXOig+kWpFzoM8aXVt0bV@mail.gmail.com>
References: <AANLkTik09f7cr7hz+fLTe6BRXOig+kWpFzoM8aXVt0bV@mail.gmail.com>
Message-ID: <1C80B4F8-A00A-4F18-9454-3435BFEFACAF@gmail.com>


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



[Rd] Orthogonal polynomial ANOVA or polynomial regression?
peter dalgaard