It's IMO a wrong theoryQuote from Retief:
This is based on actual trading or solely on your vast experience with back testing?
Probably the reason profit factor increases with bar size is because the size of profits and losses start to completely dwarf commissions and slippage with larger bars. At smaller bar sizes, commission and slippage has a much greater effect. This is also probably why the vast majority of day traders are losers - because they're dealing with bar sizes that are too small and have very small profit factors.
Just a theory.

Can you calculate the annual lower and upper bound expectancy of a stock
with a current price of $100 and with an annual historical volatility 0.35 ?
Ie. statistically worst and best expectancy after a year.
My calculations give Low=$70.47, High=$141.91
So, if you buy and hold for a year then be prepared to lose 29.53% !
Ie. you are risking 29.53% of your money.
Now do the same calc for smaller time frames...
Conclusion: the shorter the timeframe the less is the risk percent. Cf. the result I had posted previously (it has only -1.5% MDD risk for the whole year of giving back to the market from current account value...)
Compare this with the 29.53% above...

High Freq Trading is the way to go as it limits the risk substantially.
Of course one must do it right...
