I did some backtesting of my strategy of few stocks for 18 months and also tried each 6months. Backtesting was done in Ninja trader and Multicharts at for $1000/ stock trade
my strategy is ATR based strategy. I do use Futures and stocks and added commission into the calculation

1st 6 months $3351
2nd 6 months -$4250
3rd 6months $1452
and I am testing this in sim now and have NO IDEA what would be for the next 6 months. it could be even -PnL

so how do you guys use backtest results? without knowing it can reproduce a +PnL in the future.
I dont expect a exact replica of backtest in real trades, so should be closer?

You may want to look at this:

Backtesting Vs Live Trades Going through these responses, it appears that there is a fundamental misunderststanding of what backtesting is supposed to be and therefore how it's carried out. Even if backtesting is done properly, there are a number of steps between the backtest …

DbPhoenix 

You may want to look at this: Backtesting Vs Live Trades Going through these responses, it appears that there is a fundamental misunderststanding of what backtesting is supposed to be and therefore how it's carried out. Even if backtesting is done properly, there are a number of steps between the backtest …

thk you. thats valid point and responded to the other thread