Re: [R] drop1() seems to give unexpected results compare to anova()

Thanks to Mr Dalgaard for his advice and everyone else who has contributed. Inclusion of an error term at the end of sim.set$y = ... line did cure my problems with drop1() and step(). I suppose it is my own inexperience in carrying out simulations caused such gaffe. Thomas __

Re: [R] drop1() seems to give unexpected results compare to anova()

from these two functions, but not ones that were so far apart! Now I can use glm() as a workaround, but I just want to make sure there are no bugs in drop1(). Hopefully more people can give their opinions whether there is a bug. Thomas P C Chu

Re: [R] drop1() seems to give unexpected results compare to anova()

7;) rather than lm() for fitting models with normal distribution residuals. This raises the suspicion that there could be a bug in drop1() and step(), which I think uses add1() and drop1() repeatedly. Thomas P C Chu AOL

[R] drop1() seems to give unexpected results compare to anova()

845.2 128.1478 <2e-16 *** x2 1 11658.7 10448.3 795.2 220.9377 <2e-16 *** x3 1 11045.4 11061.6 806.6 197.7096 <2e-16 *** x4 1 13.4 22093.6 944.9 0.1199 0.7295 I'm not sure what is going on. I am running R 2.7.1 on Ubuntu Linux, with all components up to date. Thank you in advance