Fully agreed. If the success rate of a system is only 40% and the dollar amount of average win double the average loss then bingo.
Quote from ronblack:
Success rate means very little in this business. You can be right 95% of the time and still lose money. You can be right only 20% of the time and make a lot of money. The key is not just the success rate but the combination of success rate and avg. win to avg. loss ratio. These parameters together determine the profit factor as it is shown in this excellent paper by Michael Harris:
http://www.tradingpatterns.com/profitability.pdf
Ron