[R] glm output for binomial family

[Enrico Colosimo]

Hello,
 I am having some trouble running a very simple
example. I am running a logistic regression entering the SAME data set
in two different forms and getting different values for the deviance residual.

Just look with this naive data set:

================================================================
# 1- Entering as a Bernoulli data set
 y<-c(1,0,1,1,0)
 x<-c(2,2,5,5,8)
 ajust1<-glm(y~x,family=binomial(link="logit"))
 ajust1
#
Coefficients:
(Intercept)            x
    1.3107      -0.2017

Degrees of Freedom: 4 Total (i.e. Null);  3 Residual
Null Deviance:      6.73
Residual Deviance: 6.491        AIC: 10.49
#
# 2- Entering as Binomial data set
#
 ysim<-c(1,2,0)
 ynao<-c(1,0,1)
 x<-c(2,5,8)
 dados<-cbind(ysim,ynao,x)
 dados<-as.data.frame(dados)
 attach(dados)
 ajust2<-glm(as.matrix(dados[,c(1,2)])~x,family=binomial, data=dados)
 summary(ajust2)
#
Coefficients:
(Intercept)            x
    1.3107      -0.2017

Degrees of Freedom: 2 Total (i.e. Null);  1 Residual
Null Deviance:      3.958
Residual Deviance: 3.718        AIC: 9.104
=================================================================

It seems that there is problem with the first fitting!!!

Best
Enrico Colosimo
Dept Statistics, UFMG
Brazil