[R] Chi-square test

[Sergio Ferreira Cardoso]

Dear David and John,

Thank you for your replies. Indeed I'm using ape and nlme packages. Here it is:

> fit<-gls(fcl~mass+activity+agility,correlation=corBrownian(phy=tree),data=df,method="ML",weights=varFixed(~vf))
> Anova(fit)
Analysis of Deviance Table (Type II tests)

Response: fcl
         Df  Chisq Pr(>Chisq)
mass      1 0.1756     0.6752
activity  2 0.5549     0.7577
agility   4 3.2903     0.5105

Anyway, I have the help I was looking for. Thank you vey much.

Best regards,
Sérgio.

----- Mensagem original -----
> De: "Fox, John" <jfox at mcmaster.ca>
> Para: "Sergio Ferreira Cardoso" <sergio.ferreira-cardoso at umontpellier.fr>
> Cc: "R-help list" <r-help at r-project.org>
> Enviadas: Sábado, 21 De Janeiro de 2017 6:09:22
> Assunto: Re: [R] Chi-square test

> Dear Sergio,
> 
> You appear to have asked this question twice on r-help.
> 
> Anova() has no specific method for “gls” models (I assume, though you don’t say
> so, that the model is fit by gls() in the nlme package), but the default method
> works and provides Wald chi-square tests for terms in the model. I don’t
> understand the model formula x ~ 1 + 2 + 3 + x, however, and so I have no idea
> what gls() would do with this model, other than report an error. Perhaps you
> can show us the output — or, better yet, provide a reproducible example.
> 
> As a general matter, for 1-df terms in an additive model, the 1-df chi-square
> values reported by Anova() will simply be the squares of the corresponding Wald
> statistics (labelled “t” I believe) reported in the summary of the model.
> Although the p-value is from the upper tail of the chi-square distribution, the
> test is inherently two-sided.
> 
> Best,
> John
> 
> -------------------------------------------------
> John Fox, Professor
> McMaster University
> Hamilton, Ontario, Canada
> Web: http::/socserv.mcmaster.ca/jfox
> 
>> On Jan 20, 2017, at 8:36 AM, Sergio Ferreira Cardoso
>> <sergio.ferreira-cardoso at umontpellier.fr> wrote:
>> 
>> Dear all,
>> 
>> Anova() for .car package retrieves Chi-square statistics when I'm testing a
>> model the significance of a multivariate .gls model
>> gls(x~1+2+3+x,corBrownian(phy=tree), ...).
>> Is this Chi-square a two-sided test?
>> 
>> Thank you.
>> 
>> Best,
>> Sérgio.
>> 
>> 	[[alternative HTML version deleted]]
>> 
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