R help - Jul 2005 - Significant difference of coefficients in glm with factors?

Hi and sorry to distur,


########### Setting #################

I'm trying to use glm with factors:
> Pyr.1.glm<-glm(Pyrale~Trait,DataRav,family=poisson)
> summary(Pyr.1.glm)
Call:
glm(formula = Pyrale ~ Trait, family = poisson, data = DataRav)

Deviance Residuals: 
Min 1Q Median 3Q Max 
-1.7117 -0.8944 -0.6237 0.6390 1.5224 

Coefficients:
Estimate Std. Error z value Pr(>|z|) 
(Intercept) 1.3350 0.2294 5.819 5.92e-09 ***
TraitIns&Fong -2.9444 1.0259 -2.870 0.00410 ** 
TraitInsecticide -2.2513 0.7434 -3.028 0.00246 ** 
TraitTemoin -0.2364 0.3454 -0.684 0.49372 
---
Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` '
1

(Dispersion parameter for poisson family taken to be 1)

Null deviance: 49.813 on 19 degrees of freedom
Residual deviance: 18.532 on 16 degrees of freedom
AIC: 61.85

Number of Fisher Scoring iterations: 5
> anova(Pyr.1.glm,test="Chisq")
Analysis of Deviance Table

Model: poisson, link: log

Response: Pyrale

Terms added sequentially (first to last)


Df Deviance Resid. Df Resid. Dev P(>|Chi|)
NULL 19 49.813 
Trait 3 31.281 16 18.532 7.419e-07

############## Question ##################

I would like to know if the coefficients for the levels of the factors are 
significatively different from each other and not only from the intercept.

Do you know what function can I use and in which package can I found it?

Thanks very much for you help.

Regards.

Ghislain V.

-- 
Ghislain Vieilledent
30, rue Bernard Ortet 31 500 TOULOUSE
06 24 62 65 07

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