charting vs backtest - bar resolution vs ticks

[tb2000]

Just starting on strategies today, so I apologize for any newbieness..

I read there's an issue with OnBarClose during a real time session vs. a reload of the chart. Quoting: http://www.ninjatrader-support.com/HelpGuideV6/helpguide.html?Export1
: "In the future you reload your strategy into the chart (for whatever reason) and the 5th 1 minute bar is now a historical bar."

I understand the point (in the chart context), however:

does this imply - even though one is working of a tick stream - NT would aggregate ticks into its database to a minimum resolution of 1 minute? If that was true this would mean any intrabar logic could not be backtested on NT - am I right (I hope not)?

Or is the statement just related to charting (for whatever reasons?) and the database does record any ticks and can replay/use them on a backtest?

Thanks again!
tb

[NinjaTrader_Dierk]

>> does this imply - even though one is working of a tick stream - NT would aggregate ticks into its database to a minimum resolution of 1 minute?
Both issues are not related. Meaning, backtest runs on the selected timeframe. Nothing to worry about.

Also: not sure how the link you provided would relate...

[tb2000]

Sorry, somehow the browser displayed the wrong link in the top line;
I was referring to the Nscript section on Strategy and the Multi-Timeframe explanations on how bars were built.

I think I am concerned though: further reading the doc on backtesting a strategy I found:

• During backtest, strategies can ONLY be processed at the close of each bar

This confirms my thought (unless something in the meantime has changed and doc is out of sync): the backtester seems to either feed on minute bars or on closed bars, but not on ticks - even though I can switch its properties to run on Ticks?

Am I mistaken?

Tx again
tb

[NinjaTrader_Dierk]

- if you backtest e.g. 5 mins series then OnBarUdpate is triggered once for each 5 min bar
- if you backtest e.g. 33 tick series then OnBarUdpate is triggered once for each 33 tick bar
- there is no "look inside the bar" backtest logic

[NinjaTrader_JoshP]

If absolute realisticness is what you are seeking I recommend forward testing your strategy via either simulated on live data or the Market Replay.

[tb2000]

Josh, thanks I'll have to look into that, but will that provide the results analysis as I get from running a Backtest ?

[NinjaTrader_Dierk]

Yep, go Strategies tab->select strategy->Right click->performance

[tb2000]

I've looked into that and even though the market data replay seems to provide a results analysis, it only works of pre recorded data. I could not find if that would be applicable to just using ticks from the database (including backfill from the data vendor)?

What I need for a backtesting (and walk forward testing) plus optimization goes beyond. Like e.g. selecting the time window in order to being able to optimize in sample and back test out of sample.

[NinjaTrader_JoshP]

Unfortunately it just isn't possible to look inside a bar in a backtest. Some people have had varying success with coding a multi-time framed strategy that tries to incorporate the tick resolution. You may find it suitable for you.