Is it the people you love the most?
The ones with the most erudite comments in the "why do you want to take part in this" box?
Do you use a random number generator and make it absolutely fair?
The first to say yes?
The people with the nicest names?
Cross out all those that aren't in your target demographic?
The people who post the most?
The people who've been here longest?
The people who are most grovelly about the whole thing?
Just curious :o