O’Malley's definitely hitting his stride in these last few days leading up to the caucus

[MineralMan]

20. National convention delegates are not assigned

from individual precincts. Rather, they are assigned at the congressional district level. Individual precincts voting is pooled within each congressional district and those are the numbers that determine the number and proportion of delegates. It is at that level that the 15% rule kicks in. However, even at the individual precincts, if a candidate cannot get 15% of caucus goers, he gets no delegates to the next level and caucus goers must join with the group of another candidate.

Iowa uses a form of the "walking caucus" system on the precinct level. In Minnesota the precinct level has an election, where attendees can vote. The "walking caucus" system doesn't come into play until higher level conventions are held.

It's pretty complicated, really. It took me one cycle to completely understand Minnesota's system.