Jon, Version 3.3-0 of rms will be released within 2-3 days. It has a new option "force" for fastbw, validate, calibrate. force is an integer vector of the parameter numbers to force into every model. It is meant to work with type='individual' and its performance with type='residual' needs to be studied (I doubt if it works as you want). Suppose you have a Cox model (which does not have an intercept to include in the sequential numbering for force) like this:
f <- cph(S ~ sex + pol(age,2) + rcs(height,4)) and you want to force age into every model. You would specify force=2:3. Typing coef(f) will show you the sequential parameters in the model. Someday I'll extend this to force='age' but that's not in the current version. Note that fastbw always pools age and age^2 effects when judging significance. As always use stepwise methods at your own risk. They are dangerous to your health. If you are using Linux I can send the new version by e-mail. Frank ----- Frank Harrell Department of Biostatistics, Vanderbilt University -- View this message in context: http://r.789695.n4.nabble.com/Forced-inclusion-of-varaibles-in-validate-command-as-well-as-step-tp3324901p3325922.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.
