Theory: Random entry with a wider target vs a shorter stop.
When this theory is tested in a random environment, it breaks even. This is known. What is not known is if it profits in a Forex market. If it did, there must be something non-random about that market.
A difficulty arises with assessing a short sample such as 100. The profit would need to be obvious and steady. As a rule of thumb, given a 20 point target and a 10 point stop, the win to loss ratio would be twice as many losses as wins for break even. Similarily, a 30 point target vs a 5 point stop would produce six times as many losses as wins for breakeven. There is a margin of variance that is wider as the sample is shorter. We are now at a sample of 40 with a 25 target vs 10 stop.
Theoretically we should have the following results: 25/10 = 2.5 losses to 1 win. This is about a 71% loss rate such that a sample of 40 would yield 28.5 losses and 11.5 wins, if there was no variance. So in this case, with 15 wins and 25 losses, we have 3.5 extra wins and 3.5 fewer losses (25*3.5 + 10*3.5 = 122.5) than expected, accounting for a net of 121 pips kept. This would be a 62% loss rate for a 9% variance over our sample of 40.
For arguments sake, we will say 122.5 = 121 pips netted so far. We still need to account for th 2 pip per trade vigorish: 40*2= 80 pips that must be paid from the 121 = 41 pip profit.
So the question is, can a variance of 9% over 40 be expected? Said another way, is 3.5 extra wins, or visa versa common enough to be still considered random?
The way to determine that would be to run many samples of 40 and look at a bell curve of the variances. If it is rare, we may be seeing some non-random activity.
When paying 80 pips to make a possible 41, we would want to make very sure the profit is certain and steady. In my experience with randomness, one would have to run several thousand samples of 40 to determine the certain rarity of a 9% variance. This is where the difficulty arises, when trying to collect data from the market, especially walk-forward.
To summarize, 3.5 extra wins must be extremely rare over a sample of 40 in order for this experiment to suggest non-randomness. You must maintain a 9% variance in your favor to profit here, and it must be absolutely certain. Over a larger sample set, the variance will tend toward 0%. If the variance slips to only 7% you get eaten up after vigorish. Thus, a 2% different can kill the deal. A sample of 100 would likely not be enough to determine the certainty of maintaining a 9% variance/"edge".
If, in 8 out of 10 samples of 40 you got 3.5 extra wins, only then would you - maybe - be dealing with a profitable Forex system. It is suggested that you expand your walk forward to a set of 400, requiring 8 out of 10 to profit before comming to a conclusion.
JohnnyK