Ninjatrader and backtesting

December 13th, 2011, 04:11 AM

I'm in the process of starting with backtesting some ideas. As i'm evaluating
some programs for simple backtesting i now want to start with Ninjatrader.

I can remember by reading this forum that there are some issues with Ninja 7
with backtesting. I've read that results change and/or results are not always dependable.

Can somebody knowledgeble about Ninja say something if these issues are genuine
and do exist as perhaps i'm mistaken.

Now this is a honest question and i do not want to bash Ninja so if we can just discuss
if there are some things to watch out for or to handle in a special way.

December 13th, 2011, 11:32 AM

Someone correct me if I'm wrong, but the gist of it is...

The issue has to do with "intra-bar granularity". You can see the effect when your strategy only operates on the primary time period/frame (BarsInProgress = 0), but when you simply add a new time period your results change even though your strategy does not interact with this additional time period.

The workaround suggested by NinjaTrader is to make your entries on a higher time period such as a tick or minute chart. For example: EnterLongLimit(1, Close[0]); Which enters on the secondary time period within the strategy.

So what I do is compare the backtesting results of one day to the Market Replay results of the same day. If I get somewhat closer results then I'm a little more confident in the backtesting results as a whole. Next I will sim/paper trade the strategy with live data, which is where I am with my trading journey.

Here are some NinjaTrader Support provided links:

NinjaTrader Version 7
Strategy: [AUTOLINK]Backtesting[/AUTOLINK] NinjaScript Strategies with an intrabar granularity - [AUTOLINK]NinjaTrader[/AUTOLINK] Support Forum

I'm hopeful this will be fixed in the "next-gen" version of NinjaTrader.

December 15th, 2011, 10:24 AM

IMHO I find most people expect more than is reasonable from backtesting software. As in most things, it pays to keep things simple. I always make sure that I have very very few trades where the entry and the exit are on the same bar in the backtest results. If your software - NT7, TS, whatever - is hitting exits on the same bar as entries, I think you are asking too much of the software to cope with the situation in a way that reflects real life.

Personally I would programme my own backtesting software to be pessimistic and that if the bar hits both the target and the stop on the same bar, then it chooses the stop.

Ninjatrader and backtesting

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Ninjatrader and backtesting