Put another way, Rubin played arbitrage the way a mathematician plays poker, keeping track of cards and weighing odds so as to reduce the factor of luck. In considering whether to take arbitrage positions, Rubin would muster all available information, constantly recalculate the percentages and make a decision only when necessary. Although a player with this kind of discipline will sometimes lose -- and sometimes lose big -- over time he has a significant advantage over those who behave less rationally.