Hi, On Tue, Apr 13, 2010 at 12:51 PM, aspa <a.angelakopou...@gmail.com> wrote: > > Dear All, > > I am new to R and I would like to do the following: > > I want to fit a logistic model with 3 predictors and then perform a stepwise > regression to select the best possible model using either the AIC/BIC > criterion. > > I have used the stepAIC function which works fine but using this method only > likely candidates are evaluated (i.e. not all the models are fitted). We > should have 2^3=8 possible models. > > So I want to do the following. Write a code in R which will allow me to fit > all 8 possible models. So, i guess the first combination will be c(0,0,0) > for the 3 predictors, then c(0,0,1) for then next one and so one until 8 > models are fitted.
It seems like this little piece of code should get you going: R> expand.grid(0:1, 0:1, 0:1) Var1 Var2 Var3 1 0 0 0 2 1 0 0 3 0 1 0 4 1 1 0 5 0 0 1 6 1 0 1 7 0 1 1 8 1 1 1 It sounds like you know what you want to do next given all these possible permutations ... -steve > > I would be really grateful if I could get some advise as to how to write the > coding to tell R to fit each of these models in turn and extract the > log-likelihood for each one of them so that I will be able to calculated > AIC/BIC afterwards. > > Many thanks for your help, > A > -- > View this message in context: > http://n4.nabble.com/stepwise-regression-fitting-all-possible-models-tp1838735p1838735.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > -- Steve Lianoglou Graduate Student: Computational Systems Biology | Memorial Sloan-Kettering Cancer Center | Weill Medical College of Cornell University Contact Info: http://cbio.mskcc.org/~lianos/contact ______________________________________________ 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.
