[Limdep Nlogit List] Choice Experiment Data Entry Question

[Ali Asgary]

Hello All,
I have done a choice experiment survey in which I have a total of 12 
choices (cards) and I have given 4 cards to each respondent to rand them 
in order of preference.  Each choice has 4 attributes.  I have about 450 
surveys and I want to input my data to analyze the choices.  I know how 
to enter the data when respondents chose different options, but do not 
know what is the best strategy to enter the data into NLogit and analyze 
them.  I appreciate any idea or hint you might be able to provide on this.
Thank you very much.
Ali Asgary
York University