babies <- read.table("babies.data", header=TRUE, )
babies <- babies[babies[,"smoke"] != 9,]

attach(babies)

prem = factor(as.numeric(gestation < 7*37))
babies <- cbind(babies, prem)

model1 <- glm(prem ~ bwt, family = binomial, data = babies)
summary(model1)

model2 <- glm(prem ~ bwt + age, family = binomial, data = babies)
summary(model2)

anova(model1, model2, test="Chisq")

model3 <- glm(prem ~ age, family = binomial, data = babies)
summary(model3)


model4 <- glm(prem ~ age + smoke, family = binomial, data = babies)
summary(model4)

anova(model1, model4, test="Chisq")

pres1 = residuals(model1, type='pearson')
dres1 = residuals(model1, type='deviance')

par(mfrow=c(2,2))

hist(dres1)
hist(pres1)
plot(dres1, pres1)
plot(predict(model1), dres1)

plot(model1)