Hi, Dieter, > sessionInfo() R version 2.9.0 (2009-04-17) i386-pc-mingw32
> str(cov) 'data.frame': 40 obs. of 13 variables: $ ID : int 2 3 4 5 6 7 8 9 10 11 ... $ AMT : num 50 50 50 50 50 50 50 50 25 25 ... $ Cmax : num [1:40(1d)] 8901 5574 10496 10882 8130 ... ..- attr(*, "dimnames")=List of 1 .. ..$ ID: chr "2" "3" "4" "5" ... $ biomarker: num 3817 2542 5127 4478 3362 ... $ CRCL : num 29.2 44.5 65.5 57.1 63.3 ... $ SEX : chr "male" "male" "male" "male" ... $ WT : num 79.7 86.4 80.5 55.2 83.8 ... $ AGE : int 48 21 20 61 67 24 60 36 23 22 ... $ AGE2 : num 0 0 0 1 1 0 1 0 0 0 ... $ SEX2 : num 1 1 1 1 1 0 1 0 0 0 ... $ AGE3 : num 1 0 0 1 1 0 1 1 0 0 ... $ CRCL2 : num 0 1 1 1 1 1 1 1 1 1 ... $ WT2 : num 0 0 0 0 0 0 0 1 0 1 ... >lme(biomarker~Cmax+AGE,data=cov,method='ML',random=~1+AGE|ID,keep.data=T)->mod.lme2 Warning message: In lme.formula(biomarker ~ Cmax + AGE, data = cov, method = "ML", : Fewer observations than random effects in all level 1 groups > stepAIC(mod.lme2,scope=list(upper=~Cmax+AGE+SEX2+WT+CRCL,lower=~1+Cmax)) Start: AIC=637.53 biomarker ~ Cmax + AGE Error in terms.formula(formula, data = data) : 'data' argument is of the wrong type I also wonder if stepAIC tests random effect to each covariate (e.g. AGE, WT, CRCL...) Thanks. Jun On Thu, May 7, 2009 at 11:37 AM, Dieter Menne <dieter.me...@menne-biomed.de>wrote: > Jun Shen <jun.shen.ut <at> gmail.com> writes: > > > I changed the "method" to ML for my lme call. Now I get a different error > > when running the stepAIC > > > > Error in terms.formula(formula, data = data) : > > 'data' argument is of the wrong type > > > > What does that mean? > > The same dataset was used for an lm call and everything is fine to run > > stepAIC. > > Show sessionInfo() (do you have the recent version?) > > Show str(yourdataset) > > Show lme(.... your formula) > > Dieter > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.
