Ok, so let's say I have a logit equation outlined as Y= 2.5 + 3X1 + 2.3X2 + 4X3 + 3.6X4 + 2.2X5
So a one unit increase in X2 is associated with a 2.3 increase in Y, regardless of what the other predictor values are. So I guess instead of trying to plot of curve with all the predictors accounted for, I should plot each curve by itself. I'm still not sure how to do that with so many predictors. Any help would be appreciated. On Thu, Jul 5, 2012 at 4:23 PM, Bert Gunter <gunter.ber...@gene.com> wrote: > You have an about 11-D response surface, not a curve! > > -- Bert > > On Thu, Jul 5, 2012 at 2:39 PM, Abraham Mathew <abmathe...@gmail.com>wrote: > >> I have a logit model with about 10 predictors and I am trying to plot the >> probability curve for the model. >> >> Y=1 = 1 / 1+e^-z where z=B0 + B1X1 + ... + BnXi >> >> If the model had only one predictor, I know to do something like below. >> >> mod1 = glm(factor(won) ~ as.numeric(bid), data=mydat, >> family=binomial(link="logit")) >> >> all.x <- expand.grid(won=unique(won), bid=unique(bid)) >> y.hat.new <- predict(mod1, newdata=all.x, type="response") >> >> plot(bid<-000:250,predict(mod1,newdata=data.frame(bid<-c(000:250)),type="response"), >> lwd=5, col="blue", type="l") >> >> >> I'm not sure how to proceed when I have 10 or so predictors in the logit >> model. Do I simply expand the >> expand.grid() function to include all the variables? >> >> So my question is how do I form a plot of a logit probability curve when I >> have 10 predictors? >> >> would be nice to do this in ggplot2. >> >> Thanks! >> >> >> -- >> *Abraham Mathew >> Statistical Analyst >> www.amathew.com >> 720-648-0108 >> @abmathewks* >> >> [[alternative HTML version deleted]] >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide >> http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > > > -- > > Bert Gunter > Genentech Nonclinical Biostatistics > > Internal Contact Info: > Phone: 467-7374 > Website: > > http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm > > > -- *Abraham Mathew Statistical Analyst www.amathew.com 720-648-0108 @abmathewks* [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
