you might use default setting if you use as.factor(y)~x in rpart(), I think.
On 6/15/07, ronggui <[EMAIL PROTECTED]> wrote: > Dear all, > > I would like to model the relationship between y and x. y is binary > variable, and x is a count variable which may be possion-distribution. > > I think it is better to divide x into intervals and change it to a > factor before calling glm(y~x,data=dat,family=binomail). > > I try to use rpart. As y is binary, I use "class" method and get the > following result. > > rpart(y~x,data=dat,method="class") > n=778 (22 observations deleted due to missingness) > > node), split, n, loss, yval, (yprob) > * denotes terminal node > > 1) root 778 67 0 (0.91388175 0.08611825) * > > > If with the default method, I get such a result. > > > rpart(y~x,data=dat) > n=778 (22 observations deleted due to missingness) > > node), split, n, deviance, yval > * denotes terminal node > > 1) root 778 61.230080 0.08611825 > 2) x< 19.5 750 53.514670 0.07733333 > 4) x< 1.25 390 17.169230 0.04615385 * > 5) x>=1.25 360 35.555560 0.11111110 * > 3) x>=19.5 28 6.107143 0.32142860 * > > If I use 1.25 and 19.5 as the cutting points, change x into factor by > >x2 <- cut(q34b,breaks=c(0,1.25,19.5,200),right=F) > > The coef in y~x2 is significant and makes sense. > > My problem is: is it OK use the default method in rpart when response > varibale is binary one? Thanks. > > > -- > Ronggui Huang > Department of Sociology > Fudan University, Shanghai, China > > ______________________________________________ > [email protected] 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. > -- WenSui Liu A lousy statistician who happens to know a little programming (http://spaces.msn.com/statcompute/blog) ______________________________________________ [email protected] 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.
