Hello. Im hoping someone can help with a grouping question related to the "random=" statement within the nlme function. How do you specify that some grouping levels are inner to others? I tried several things, given below.
Lets say I have a data frame with five variables, resp, cov1, ran1, ran2, group1, and group 2. The formula is resp~cov1 + ran1 + ran2, where the ran are random variables. The data is of length 80, and there are 4 unique factors in group1 and 20 unique factors in group2. These are factors related to ran1 and ran2, respectively. The difficult part is that I want to estimate only 4 random variables for ran1|group1 and the full 20 for ran2|group2. I have tried many ways, and I cannot find a way to do this. Is there a way? Can someone suggest a code snippet? First I tried making the data frame a groupedData object, so that group2 is inner to group1, as it should be. Then I used the statement: random = as.formula(ran1+ran2~1). But this produced 20 estimates for both ran1 and ran2. I have also tried it without the data frame as a groupedData object, using the following: random = list(group1= c(ran1~1, group2=ran2~1)). But this gave only 4 estimates for ran2. I also tried: random = list(c(group1= ran1~1, group2=ran2~1)), but this just gave a parse error message. Any suggestions would be greatly appreciated. Is it even possible to do what I want to do? John ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
