[R] ANOVA "Types" and Regression models: the same?

Liaw, Andy andy_liaw at merck.com
Tue Mar 2 14:32:02 CET 2010

If memory serves, Bill Venables said in the paper cited several times
here, that there's only one type of sums of squares.  So there's only
one type of "ANOVA" (if I understand what you mean by ANOVA).

Just forget about the different types of tests, and simply ask yourself
this (hopefully simple and straight forward) question: Which pair of
models when compared will answer the question you have at hand?  It's
not sufficient to just ask: "Is factor X significant?"  It depends on
what else is in the model you're entertaining.

I think it's high time to retire the archaic concept of the different
types of sums of squares.  IMHO they are the biggest red herrings in


From: Ravi Kulkarni
> Hello,
>   I think I am beginning to understand what is involved in 
> the so-called
> "Type-I, II, ..." ANOVAS (thanks to all the replies I got for 
> yesterday's
> post). I have a question that will help me (and others?) understand it
> better (or remove a misunderstanding):
>   I know that ANOVA is really a special case of regression where the
> predictor variable is categorical. I know that there can be 
> various types of
> regression models commonly called "stepwise, add, remove...", 
> where one
> controls which predictors are added to the regression model 
> and in what
> order.
>   Is this what the various "Types" of ANOVA correspond to? I 
> mean that I
> think of my ANOVA as a regression model (a General Linear 
> Model) and the
> various ways of entering predictors as the various ANOVA "Types".
>   Hope that makes sense...
>   Ravi Kulkarni
> -- 
> View this message in context: 
> http://n4.nabble.com/ANOVA-Types-and-Regression-models-the-sam
> e-tp1574654p1574654.html
> Sent from the R help mailing list archive at Nabble.com.
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