Q: I want to test a trading model, bet sizing method where I can adjust bet according to if win/lose and also stop, based on probability of win or lose. Are there any good programs to help. Can I do this with spreadsheet?

A: Position sizing based upon probability of winning is suicide. For example, suppose you have 9 1R winners and 1 10R loser. That would be a negative expectancy and there is no way position sizing could turn it into a long term winner, but it is right 90% of the time. If you are basing your position sizing off of the probability of winning, then I can only assume that is how you gauged the quality of your system, as well.

I have created a concept/equation to calculate the quality of your system. My new book, The Definitive Guide to Position Sizing (which has not yet been published) deals with this concept in greater detail. I suggest that you read through my book when it becomes available to make sure that your system is even worth trading before you try to lay a position sizing method over it.