[R-lang] p-values for factors using lmer & mcmc

[Andy Fugard]

T. Florian Jaeger wrote:
> 
> On 9/3/07, *Andy Fugard* <a.fugard at ed.ac.uk <mailto:a.fugard at ed.ac.uk>> 
> wrote:
> 
>     [...]  Faraway (2006, p. 13) mentions in passing
>     that "We would normally avoid using the t-tests for the levels of
>     qualitative predictors with more than two levels."  His example is for
>     Gaussian multiple regression; perhaps that's important?
> 
> that is because the levels of a qualitative predictor are often 
> collinear. collinearity is bad for tests that use the standard error 
> estimate of the coefficient. so, those issues should go away after you 
> center your predictors and go through other measures to remove/reduce 
> collinearity in your model.

Aha!  Is there a standard reference for this?

Many thanks,

Andy

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Andy Fugard, Postgraduate Research Student
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