There’s an excellent thread here: http://mafia-wars.org/viewtopic.php?f=10&t=216, started by someone who has determined the basic formula used in fights. He also has a “combat calculator” online that will tell you how your equipment and stats compare to average for your level (http://www.mafia-wars.info/index.php). MW does NOT in my opinion calculate fights the way I would expect. For instance, the equipment chosen when you attack is also the same used for defense in that same fight, and the ATK and DEF values of each item are simply added, rather than your best defense weapons being used for the defense side of the equation. That means… an AR-15 is *worse* to have than a Midas Knife, because the total ATK+DEF is lower. total value.

Also, your Attack and Defense skill points are simply added together and that total used in
calculating your strength, whether you are attacking or defending. While someday it may make
a difference, today putting points in either one has the same effect.