On Jun 6, 2014, at 11:16 AM, Nwinters wrote: > I have a variable coded in Stata as follows: > ** > *gen sat_pm25cat_=. > replace sat_pm25cat_= 1 if (sat_pm25>=4 & sat_pm25<=7.1 & sat_pm25!=.) > replace sat_pm25cat_= 2 if (sat_pm25>=7.1 & sat_pm25<=10) > replace sat_pm25cat_= 3 if (sat_pm25>=10.1 & sat_pm25<=11.3) > replace sat_pm25cat_= 4 if (sat_pm25>=11.4 & sat_pm25<=12.1) > replace sat_pm25cat_= 5 if (sat_pm25>=12.2 & sat_pm25<=17.1)
Apparently Stata handles overlapping definitions somehow. (7.1 items would be ambiguously define.) I suspect you can duplicate that intended effect with: sat_pm25cat_ <- findInterval(sat_pm25, c(4, 7.1 ,10, 11.4,12.2, 17.1) ) > > gen satpm25catR= "A" if sat_pm25cat_==1 > replace satpm25catR= "B" if sat_pm25cat_==2 > replace satpm25catR= "C" if sat_pm25cat_==3 > replace satpm25catR= "D" if sat_pm25cat_==4 > replace satpm25catR= "E" if sat_pm25cat_==5 satpm25catR <- factor( LETTERS[1:5][ sat_pm25cat_ ] ) > *** > > my model for R is: > ## > *glm.PM25linB <-glm(leuk ~ satpm25catR + sex + ageR, data=leuk, > family=binomial, epsilon=1e-15, maxit=1000)* > ## > > In the summary, satpm25catR is being reported as all levels: > > <http://r.789695.n4.nabble.com/file/n4691823/Screen_Shot_2014-06-06_at_2.png> > > *What I want is to make "A" the reference level, how do I do this??* It would be the reference level by default since factors are sorted lexically. -- David Winsemius Alameda, CA, USA ______________________________________________ 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.
