Survey Help

[Amyunimus]

I'm working on a survey now that asks people to compare two places. I have over 2,000 different pairs to have compared, so I'd like to divide this up into many different versions of the survey, so that each person will only answer 200 different questions.

I want to control for which pairs each subject sees-- that is, drawing up 120 random pairs from a list won't do. I've made a list of which 200 comparisions each person will make, and want to be able to input this information into the site. So, person 1 answers the first set of 200 questions, person 2 answers the second set of 200 questions etc etc. until all 2,000 questions have been answered. Then the process will start again until all 2,000 questions have been answered 4 or 5 times each.

My question is how do I make it so each user gets a different set when they access the same site?

Any suggestions?