Hmm... The results thus far have been quite uniform. Of course the basic setting of the poll might remove the first type completely, as they aren't likely to encounter polls hidden in the forums. However, there shouldn't be any obstacles for the other types. Basically the options can be divided in two: Registering just in case and registering only when necessary.

Both types should be as likely to vote, considering the registration would be historical always. Unless the just in case type is less likely to actually post at all.

Since this site doesn't require registration for any functionality aside from posting, in theory almost all the zero post members could be counted to belong into the first type. Some fraction could of course be people who registered to actually post something, but then refrained from posting after all, for whatever reasons.