thank you for your reply!
i don't think i was clear about my problem, but what you suggested is something what i tried to do.
ID's are all different from each other (we do clinical research and ID's are identifying numbers of our volunteers).
what i did was assign number 1 to an ID if it is...
i have the following problem that i can't figure out.
i have a set ID's which i pseudo-randomly split into 2 subsets A and B. let's say for the sake of simplicity i did it twice only, so i have subsets A&B and A`&B`. the sizes in the different splittings are the same - not sizes of A and B...