Hi I am trying to estimate stated preferences for Tv sets by using mlogit. The choice set is designed as with 4 attributes: [ brand(has 4 levels), technology(has two levels), class[has 4 levels), price(has 4 levels)] There are 16 choice sets with 4 alternatives each one (i.e. each respondent has evaluated 64 cards in total). Therefore, there are 64 rows in the table below. The data in csv file looks like this: Mode Brand Technology Class Price 0 1 1 1 1 1 2 1 2 2 0 3 2 3 3 0 4 2 4 4 0 2 2 4 2 0 1 1 3 1 1 4 1 2 4 0 3 2 1 3 0 3 2 2 3 1 4 1 3 4 0 2 2 1 2 0 1 1 4 1 0 4 1 3 4 1 3 1 2 3 0 2 2 1 2 0 1 2 4 1 1 1 1 1 4 0 3 2 3 2 0 4 2 4 3 0 2 1 2 1 0 2 1 4 3 0 4 2 2 1 1 3 1 1 4 0 1 2 3 2 0 3 1 4 2 0 1 2 2 4 1 2 1 3 1 0 4 2 1 3 0 4 1 1 1 1 2 2 3 3 0 1 2 2 2 0 3 1 4 4 0 1 1 1 3 0 4 2 4 2 1 2 1 2 4 0 3 2 3 1 1 2 2 4 4 0 3 2 1 1 0 1 1 3 3 0 4 1 2 2 0 3 2 2 1 1 2 2 1 4 0 1 1 4 3 0 4 1 3 2 0 4 1 3 2 0 1 2 4 3 0 3 1 2 1 1 2 2 1 4 0 3 2 3 4 0 1 1 1 2 0 4 2 4 1 1 2 1 2 3 0 4 2 2 3 0 2 1 4 1 0 1 2 3 4 1 3 1 1 2 0 1 2 2 2 0 3 1 4 4 0 4 2 1 1 1 2 1 3 3 0 2 2 3 1 1 4 1 1 3 0 3 1 4 2 0 1 2 2 4 R has already read and save the data,but when I come to the line: DataR$mode.ids<-factor(rep(1:64,1),labels=c("brand","technology","class","price")) I get the following error: Error in factor(rep(1:64, 1), labels c("brand", "technology", "class", I guess it has to do with the setting up of my file or the coding in R. How can I do it right? Each respondent chose 16 times among 4 different cards every time.. Kind regards, Andrea [[alternative HTML version deleted]]