[R] GLM different results with the same factors

[gaiarrido]

I've read something about this problem, but I don't know how can i avoid this
problem.
Why the order of the factors give different results? I suppose it's because
the order of the factors, i've just changed "lcc" from the first position to
the last in the model, and the significance change completely 

> modo<-glm(prevalencia~*lcc*+edadysexo/lcc+edadysexo/mes,binomial)
> anova(modo,test="Chisq")
              Df Deviance Resid. Df Resid. Dev P(>|Chi|)   
NULL                            524     206.97             
lcc            1  10.5715       523     196.40  0.001148 **
edadysexo      2   1.0725       521     195.32  0.584929   
lcc:edadysexo  2   3.7752       519     191.55  0.151433   
edadysexo:mes  9  18.2981       510     173.25  0.031868 * 

> mode<-glm(prevalencia~edadysexo/lcc+edadysexo/mes+*lcc*,binomial)
> anova(mode,test="Chisq")
              Df Deviance Resid. Df Resid. Dev P(>|Chi|)   
NULL                            524     206.97             
edadysexo      2   9.9165       522     197.05  0.007025 **
lcc            1   1.7275       521     195.32  0.188732   
edadysexo:lcc  2   3.7752       519     191.55  0.151433   
edadysexo:mes  9  18.2981       510     173.25  0.031868 * 

Ijow can i know what's correct? when i test this two factors separately in a
lm (lcc is continuos) and in a chisq.test (edadysexo is categorical) both
are significant, and in the model just one of them is significant.

Thanks very much


-----
Mario Garrido Escudero
PhD student
Dpto. de Biología Animal, Ecología, Parasitología, Edafología y Qca. Agrícola
Universidad de Salamanca
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