Hi again Jasjeet, Walter, I have a further question about an error message I get when running multinomRob. I am simulating a dataset where I look at the effect of making a previous categorical choice on the probability of making the same choice later on. Given the following code:
n <- 20 choice <- c("A","B","C") intercepts <- c(0.5,0.3,0.2) prime.strength <- rep(0.4,length(intercepts)) counts <- c() for(i in 1:length(choice)) { u <- intercepts[1:length(choice)] u[i] <- u[i] + prime.strength[i] counts <- c(counts,rmultinomial(n = n, pr = multinomLogis(u))) } dim(counts) <- c(length(choice),length(choice)) counts <- t(counts) row.names(counts) <- choice colnames(counts) <- choice data <- data.frame(Prev.Choice=choice,counts) for(i in 1:length(choice)) { data[[paste("last",choice[i],sep=".")]] <- ifelse(data$Prev.Choice==choice[i],1,0) } multinomRob(list(A ~ last.A , B ~ last.B , C ~ last.C - 1 , ), data=data, print.level=1) I get the following error: multinomRob(): Grouped MNL Estimation Error in if (logliklambda < loglik) bvec <- blambda : missing value where TRUE/FALSE needed In addition: Warning message: NaNs produced in: sqrt(sigma2GN) It's not clear to me what this error means, or why the resulting dataset would be problematic for MLE estimation. Many thanks once again! Roger ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.