Thanks for the clear explanation Terry! It gets ugly for many factanal applications, where you are dealing with 300 variables…
One question: what would be wrong with auto generating the formula from a matrix call? That way the matrix call gets the benefit of returning scores. Also: you say a person using the non-formula version might know what they are doing. My guess is that is not the case; Most non-experts do just this. And an expert could still not get scores back, no? best, tim PS: If anyone who cares about documentation is reading, it would be lovely to include a valid example for getting scores in a realistic dataset with NAs… where the na.action has to be set. On 7 Feb 2012, at 2:40 PM, Terry Therneau wrote: >> Does factanal() force the user to use the formula interface if they >> wish to specify an na.action? > > Short answer: yes. > > Long answer: The handling of na.action is a built in part of the formula > processing functions, so it's automatic when dealing with a formula. > There are also downstream effects on predict() and resid() that are > worked out for the formula case, but aren't clear otherwise. So- > a. it would require extra programming and thought to work it out for > matrix vector input, and the "right" answer isn't clear (it's harder > than you might think). > b. the usual assumption when a matrix/vector is given directly is > "the user knows what he's doing, or wouldn't have called it this way." > For many routines, the matrix input is a speedup for simulations. > c. factanal is unusual -- most routines split the two inputs. > glm=formula interface & glm.fit=matrix interface, lm & lm.fit, coxph & > coxph.fit, .... > > Terry Therneau > > ______________________________________________ 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.
