x=c(-1,-1,0,0,0,0,1,1,1)   ## independent variable
y=c(2,3,6,7,8,9,10,12,15)  ##   dependent variable

fit1 <- glm(y~x, family=poisson(link=identity))

fit1 

yhat=predict(fit1)    ###predict the repsonse

dev.terms <- y*log(y/yhat)

sum(dev.terms)

data.frame(x,y,yhat, dev.terms)