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...I heard about nlsystemfit, but I don?t know how to run it exactly. I have tried the following code, but it doesn?t really work: f1 <-y~ x[1]^2-x[2]^2-6 f2 <-z~ x[1]-x[2]-3 f <- list(f1=0,f2=0) nlsystemfit("OLS",f,startvals=c(0,0)) Thank You in advance for your help. Evgeniq Petrova

Hi there, I cannot seem to figure out how to access the elements of a list if those elements are a matrix. For example I have a the following list df.list <- vector("list", 3) and I have made each of the elements a matrix as follows for(i in 1:3){ assign(paste("s",i, sep=""),matrix(0, nrow = 20, ncol = 5, byrow = FALSE, dimnames = NULL)) } # and then insert

Dear all, I am struggling with a problem which I have been reading on the forums about and it did not seem to me that there is a precise answer to my question. However, I still hope there is one. I am working with http://timss.bc.edu/ PIRLS data and trying to conduct multilevel analysis. There are different weights for each level of analysis in the PIRLS dataset (e.g. there is a school