Backtesting Valid?

I'm looking for an entry that has a 90% or better success rate. I've grown tired of losing trades
Suppose I have a system/method I've developed that has a risk:return of 33:165. And I feel I can get a 90% win ratio.

So I backtest methodically... for 27,000 events!

I work the testing conservative... assuming I won't fill unless the gap is ~2 pips and I can't close unless the gap is ~2 pips...
My win/loss ratio turns out to be ~91%

My win/loss ratio turns out to be >> 91% when I begin live trading... 95+% over 170 trades....

What is my confidence.... I don't remember what to punch in from my college statistics class.... but what are my chances of maintaining 91% based on that history? Any probability experts???

90x33 = 2970
10x(-165) = (-1650)

Your probability is N/A .

But seriously, we could go in to the whole equation for calculating your statistics and get your STDV, Variance, and derive max drawndown etc, however it seems you have tweaked your system through back testing, pretty much invalidating the data imo.

Test the account on a live micro account to get better data. The problem still is the market is always changing, so using normal statistics really do not tell the full story. I could tell you your system will win 90% of the time based on past data, but the fact is it is far less likely to do so because of an every changing market.

However, you can still plan for the future and see what you will require to keep the system running and profitable. My advice is to see gauge why your system works, what conditions it works in and find out what would need to happen to change these conditions. Once you have an overall idea of how the system should behave, you can monitor it and the market and make more informed decisions... just my 2cp.

Worth more than 2 cents any day.

hmm... it's been awhile, but thanks for the replys
I guess what I was looking for was the statistics formula where you can compute a margin of error.

My numbers are more realistic now from live trading the method. I got a surprise when I was able to migrate from the micro account and begin trading mini lots! Fill rate was an amazing boost! That ~2 pip buffer was too low in live trading on a micro account

I now shoot to maintain an 85% win ratio with an expected win at $27 and expected losses at $91 each. My max loss risk is $100.

It's funny but I now have so many trades in my spreadsheet that even though I beat the 85% ALMOST every week... I can never get the total pct to go up to 86%...

I can't seem to improve the win $$$ but reducing the losses has become the Holy Grail!