Sorry about the delayed response. I do the preliminary selection, based on the reasons provided (with as little personal opinions as possible). I cut out nominations where the only stated reason is "they're a good person" or "they're really fun" or something like that. Then I take all of the nominations and summarize them into a few sentences, so staff are not swayed by the amount that was written. Then staff discusses the nominations, based on past infractions of the rules, current behavior, stated nomination reasons, etc. Then, whoever's left standing is voted upon.
More or less.
Incidentally, February nominations are open. PM me if you've got 'em!