If you want to know if a system has a long term genuine chance of winning then you need to calculate the archie (chi-square) score.

I have systems which have had 700 bets and are up by 20% but the archie score was very low meaning that luck had a lot to do with the results. And sure enough the next 700 bets showed a huge loss.

If you are going to be serious about betting a system then do the calcs and see what you come up with. If the archie score is anywhere under 5 then you need more results to work out whether the system is worth following OR the system is showing a result which is based on luck.

My current cutoff points for any systems I use is an archie score of at least 5 and at least 200 bets in the live test period (not back fitted data).

Just thought I would mention that the archie score shows whether the results were due to luck. If you have an archie score higher then 5 and the system is showing a loss then its confirming that the system will never make a profit.

Good Luck