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I've been a supporter of NT for a little while now. Mainly because I haven't had the problems others have had. That is starting to change. This latest issue (Version 7) is causing me to re-think whether I want to continue with NT or try to find a new platform to trade from.
I've read that others have had issues with backtesting not being very good with NT. Mostly revolving around CalculateOnBarClose set to false. Well, my problem with a recent strategy is with COBC set to true. Which *should* allow me to backtest stuff and be somewhat reliable.
I spent quite a bit of time writing, then optimizing and walking forward to get good results on a particular strategy (again, COBC set to true) with tick charts. But then, when it came to run the strat in sim, I quickly realized that the results from sim and backtesting were off. And by a long shot in most cases. Not simply slippage, but missing trades, or vastly different entries/exits. So much different that it basically renders backtesting almost useless. I mean. In backtest I could have a loss of $500 on a particular day and in sim mode I've gained $1000 on that same day!!
Am I asking too much for NT to be close (with the exception of expected slippage) with backtesting and sim/live trading? I've been pulling my hair out for days now and can't seem to get the two to come to an agreement for very many trades.
Can anyone offer anything about this? What the heck am I overlooking, or is NT really this flawed? I've invested so much time with it, and have some other strats that work fine and dandy. I'd hate to start over with a new platform. But this is completely unacceptable imo. Might as well not even backtest with the discrepancies I'm getting.
Thanks
Can you help answer these questions from other members on NexusFi?
Post your code and specific instructions to reproduce such as bar type and size if you want someone to look it over... But, generally speaking, I would not trust NT backtest results very much.
As you can probably understand, I'd rather not share my code. Can I ask-- since you moved to MultiCharts, are you having backtesting issues? I'd hate to switch platforms, but this is a big enough deal to make me think long and hard about it.
The only bars that backtest with integrity to live trading are time based using market orders. COBC=false is a total waste of time, too. This is a fact of life with NT. And, I don't know why you are so surprised. I believe NT discloses this in the documentation.
I'm not sure if things are different with other platforms.
I don't know either. I guess I was under the impression that using COBC=true would make backtesting relevant to live. Live and learn, I guess.
I'd rather not switch from tick to a minute chart, but I'm going to try that this afternoon and see if it gets me any closer to similar backtest/live results.
Your assumption about COBC=true is as correct as it can be. If you enter at barclose then that's equivalent to COBC=true.
Using anything other than timebased charts can as you noticed produce different results live versus historic. Something I do using nonTimebased charts is to set the Session begins and Session ends parameters of the chart properties (nt6.5). Session begins = 12:00 am and Session ends = 11:50 pm. This means every day starts exactly the same every time and is not dependent on the number days I backfill and further this minimizes the differences you are frustrated with.
Hopefully this will help. It has helped me considerably. Bear in mind that I believe the problem will never go away completely. You can only minimize it's effect.
Yah, this is something I've already been doing after being confronted with another issue trying walk-forward optimizing. Unfortunately, even when using a session that starts at 2am and ends at 11pm, I get these crazy discrepancies.
When the market is over today, I'm going to do some testing with 1-minute charts and see if that gets me any closer.