This is dangerous because prevalence is an ill-defined concept. Most discussions of prevalence fail to understand conditioning completely.
If you must, you can do this with an appropriate offset() term. Frank > > Hi, I am wondering if there is a way to specify the prevalence of events > in logistic regression using lrm() from Design package? Linear > Discriminant Analysis using lda() from MASS library has an argument > "prior=" that we can use to specify the prevalent of events when the > actual dataset being analyzed does not have a representative prevalence. > How can we incorporate this information in lrm()? The concern I have is if > my dataset does not have a representative prevalence, then the probability > generated by lrm() will not be meaningful. Thanks > > John > > ______________________________________________ > 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. > ______________________________________________ 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.
