[R] How to find the accuracy of the predicted glm model with family = binomial (link = logit)

[Weidong Gu]

Andra,

You can transfer the probabilities into class membership by setting up
a cut-off value, usually 0.5.

set.seed(3)
x<-rnorm(100)
y<-rbinom(100,prob=1/(1+exp(x)),size=1)
model<-glm(y~x,family=binomial(link=logit))
pred<-ifelse(predict(model,type='response')>0.5,1,0)
table(pred,y)


Weidong Gu

On Fri, Aug 26, 2011 at 12:58 AM, Andra Isan <andra_isan at yahoo.com> wrote:
> Hi All,
>
> When modeling with glm and family = binomial (link = logit) and response values of 0 and 1, I get the predicted probabilities of assigning to my class one, then I would like to compare it with my vector y which does have the original labels. How should I change the  probabilities into values of zero and 1 and then compare it with my vector y to find out about the accuracy of my prediction?
>
> Thanks,
> Andra
>
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