Dear list:

I am trying to merge two files together from output I get based on the coef() command. Here is what I am running into.

I have two simple linear mixed models

> mod1.lme<-lme(math~year, data=sample, random=~year|childid/schoolid)

> mod2.lme<-lme(math~year, data=sample, random=~year|childid)

I then call the coefficients and store them in the following objects using

> mod1.coef<-coef(mod1.lme, level=2)

> mod2.coef<-coef(mod2.lme)

The problem is that the IDs are different for the two dataframes and I cannot seem to figure out how to make the merge happen nicely. For example, this is output from mod1.lme for the first 5 students

> mod1.coef[1:5,]
                     		(Intercept)      year
2020        /273026452     0.03923346 0.9575926
2020        /273030991     0.91772318 1.0773731
2020        /273059461     0.43865139 1.0111789
2020        /278058841     1.11292376 1.0526057
2020        /292017571     1.09661340 1.0774692

As opposed to out for the first 5 cases in mod2.coef

> mod2.coef

         		 (Intercept)      year
101480302    -1.13483082 0.7023644
173559292     0.52818576 0.8639216
174743401    -1.18038537 0.6824612
174755092     0.04760782 0.7402835
179986251    -2.42848405 0.5677182

You can see that the ID variable for the first output includes the grouping variable "schoolid" followed by a "/" and then the "childid".

I am interested in exploring the differences in the growth trajectories between the two models and would like to merge the two datasets to be able to do so. What do I need to do to somehow eliminate the schoolid and "/" from mod1.lme so that I can use the merge() command?

Thanks,


Harold C. Doran
Director of Assessment
One Massachusetts Avenue, NW · Suite 700 
Washington, DC 20001-1431
202.336.7075


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