Definition of aggression factor
This is a statistic very often used in the trackers of poker's. It is a proportion of call and raises to the opponent's calls. For example, if an opponent has bet twice, raised twice and called twice, we will do (bet 2 + Raise 2)/ call 2 so 4/2 so 2. An aggression factor of 2 is seen as an average. At 1 and less you are too passive and at 3 and more you are very aggressive. This statistic should not be confused with aggression frequency which is a little less used.
A practical example of aggression factor
How can this statistic help me? To make the right decisions, of course! Let's take an example on the river. You have just completed a straight on the river, but the map that completes the sequence also completes the color (flush). You decide to bet your hand to be called by three of king or both pairs. After all, your hand is very strong. After your bet, your opponent will call you check-raise! What to do? Taking a look at aggression factor might be a good idea. If your opponent has an aggression of 1 or 0.8, chances are he has the flush. If he has say 8, it's very possible that he's on a bluff to get you to fold!