re: Poker & Poker Tracker questions
Aggression factor is calculated as (# of times bet or raise) divided by (# of times call). Checking or folding do not factor at all (this is all post-flop, by the way). So if your stats on someone has them with an aggression factor of infinity, it means you haven't witnessed them call
a bet post-flop. And yes, this is almost always due to a small sample size. AF takes a long time to converge, so it's not accurate until you have a lot of hands on someone. PT3 uses a new stat, aggression frequency, which takes into account checks and folds.
An AF of 1.0 means a person bets or raises as much as he calls. Less than 1 means he calls more, or is more passive. Between 1 and 1.5 is average. Greater than 1.5 or 2.0 is considered aggressive.
There is a great Poker Tracker reference thread here: