Hi, I am a student from Korea. Currently I use Support. CEs package to conduct a choice-based conjoint analysis, but encounter some problems.I hope I can get a solution here. Here's my problem.I 've done the design matrix data set, and have a respondent data set. But when I try to use the "make.design.matrix" function to creat a dataset that is suitable for the function clogit, there is always an error occur. The error is "Error in order(my.respondent.dataset$ID): argument 1 is not a vector". I want to know why this error happens, and how to correct. And the attached images are design matrix data set (desmat1p), respondent data set (persimmons1), and the code & error I'll appreciate if you can reply as soon as possible. best regards, Mia. -------------- next part -------------- A non-text attachment was scrubbed... Name: desmat1p.png Type: image/png Size: 14944 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20150112/1f7d0dd7/attachment.png> -------------- next part -------------- A non-text attachment was scrubbed... Name: persimmons1.png Type: image/png Size: 13352 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20150112/1f7d0dd7/attachment-0001.png> -------------- next part -------------- A non-text attachment was scrubbed... Name: ??? 1.png Type: image/png Size: 5633 bytes Desc: not available URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20150112/1f7d0dd7/attachment-0002.png>