On 10/3/08, hadley wickham <[EMAIL PROTECTED]> wrote:
> On Fri, Oct 3, 2008 at 8:04 AM, eugen pircalabelu
> <[EMAIL PROTECTED]> wrote:
> > Hi List,
> >
> >
> > I have the following problem: I am using the multilevel package and
> make.univ function for available in the package and then xyplot from lattice
> and I want to know how could I be able to use the "coefficient" for the
> straight line that passes the data ?
> >
> > Example from help:
> >
> > library(multilevel)
> > data(univbct) #a data set already in univariate or stacked form for job
> satisfaction
> > TEMP<-univbct[3*1:495,c(22,1:17)] #converting it back to multivariate form
> > TEMP2<-make.univ(x=TEMP,dvs=TEMP[,c(10,13,16)]) #transforming it to
> univariate form again
> >
> >
> xyplot(MULTDV~TIME|as.factor(SUBNUM),data=TEMP2,type=c("p","r","g"),col="blue",col.line="black",xlab="Time",ylab="SAT")
> # taken from Bliese Paul – Multilevel Modeling in R
> >
> > Now I want to be able to identify those SUBNUM that have a downwards trend
> like (for eg SUBNUM 7) without picking them by inspecting the plot. Is there
> some way how I could access these coefficients for this apparently regression
> line?
>
>
> You'll need to fit the models yourself, and then inspect the
> coefficients of the results. Here's one way using the plyr package:
Another option is 'lmList()' in the nlme (or lme4) package:
fm <- nlme::lmList(MULTDV~TIME|as.factor(SUBNUM), data=TEMP2, na.action=na.omit)
neg <- names(which(sapply(fm, coef)["TIME", ] < 0))
xyplot(MULTDV~TIME|factor(SUBNUM), data=TEMP2, type=c("p","r","g"),
col.line="black",subset = (factor(SUBNUM) %in% neg))
-Deepayan
> [...]
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