NT Providing Bad Price & Volume Data in OnMarketData!!!

October 17th, 2010, 04:38 PM

Zondor

hi RJay,

Please post sample code or pseudo code showing correct method to use, thanks!

No problem, here is a sample.

-----------------------------------------------------------------------------------------------------------------------

protected override void OnMarketData(MarketDataEventArgs e)

{

if (e.MarketDataType == MarketDataType.Ask )theAsk = e.Price; // Add this line

if (e.MarketDataType == MarketDataType.Bid )theBid = e.Price; // Add this line

if (e.MarketDataType != MarketDataType.Last)return;

// if (e.MarketData.Ask != null) theAsk = e.MarketData.Ask.Price; // comment out this line

// if (e.MarketData.Bid != null) theBid = e.MarketData.Bid.Price; // comment out this line

if(theBid <= 0 || theAsk <= 0) return;

if (e.Price == theAsk) { netVolUp += e.Volume; }
else if (e.Price == theBid) { netVolDown -= e.Volume; }

}

------------------------------------------------------------------------------------------------------------------

RJay

October 17th, 2010, 10:09 PM

aviat72

I think the conversation confirms what I wrote in the previous post. The FirstTickOfBar is only valid in the context of OnBarUpdate().

This is the problem. Volume[0] works ok in OnBarUpdate(). If counting your own volume from OnMarketData() the first tick of the bar will be dropped. If the number of contracts in that tick is one, your count will be less that Volume[0] or the VOL indicator by one. If there were three contracts, your count will be three less than VOL shows. This is a problem that shows up if using FirstTickOfBar in OnBarUpdate() or if using code like if(CurrentBar != activeBar) in OnMarketData() to start your count in NT7.

Dan

October 18th, 2010, 10:42 AM

RJay

In OnMarketData, NT provides temporary values for coders for volume and price, for bid, ask and last.

These values are accessed with the following code.

-----------------------------------------------------------------

e.MarketData.Ask.Price

e.MarketData.Bid.Price

e.MarketData.Last.Price

e.MarketData.Ask.Volume

e.MarketData.Bid.Volume

e.MarketData.Last.Volume

----------------------------------------------------------------

If you are using any of these coding queries in your indicators, your indicators are displaying bad data!!!

Here are a few examples of what is going wrong:

When several ticks arrive at the same time, NT tends to assign all of those trades the same volume even though the trades all had different volumes.

Also, When the market trends strongly in one direction, the bid and ask prices offered fall behind the live market. This
results in last trades for both the bid and the ask, to be tallied, either, all for the bid, or all for the ask.

This really screws up stuff like volume delta calculations!!!!

This problem is persistent in both NT 6.5 and NT7.

The workaround for this problem is to create your own temporary store values from e.Volume and e.Price.

Below are the lines of code that I now use in my indicators.

---------------------------------------------------------------------------------------------------

if (e.MarketDataType == MarketDataType.Ask)ePriceAsk = e.Price;

if (e.MarketDataType == MarketDataType.Bid)ePriceBid = e.Price;

if (e.MarketDataType == MarketDataType.Last)ePriceLast = e.Price;

if (e.MarketDataType == MarketDataType.Ask)eVolumeAsk = e.Volume;

if (e.MarketDataType == MarketDataType.Bid)eVolumeBid = e.Volume;

if (e.MarketDataType == MarketDataType.Last)eVolumeLast = e.Volume;

---------------------------------------------------------------------------------------------------

After I made these changes and put the temporary patch for the CurrentBar/FirstTickOfBar bug into my indicators, my NT7 indicators are now matching the Time & Sales display window tick for tick.

I plan to post a problem report on the NT forum this Monday and hope they will take steps to resolve this issue.

I am also building an indicator that will send all of the bad data mismatches to the output window to help NT confirm the problem.

Comments and feedback are appreciated,

RJay

FYI, All the Bid/Ask volume indicators I have posted here, on this forum, have this problem. I will update them when NT7 is finally released.

Just to clarify, This problem is not about your datafeed, it's about how your indicators are constructed.

If your indicators are using bad data values, it won't matter what datafeed your using.

Your indicator displays on the chart will be wrong!!!

Test this for yourselves.

Attached is a test indicator that displays differences between NT's temporary store values and your live feed.

Just open your output window and see what I'm talking about. Every display update is a mismatch.

Seeing is Believing,

RJay

NinjaTrader · October 18th, 2010, 02:10 PM

RJay,
You are correct that if you are to use OnMarketData() and you wish to do value comparisons you should store local values in your indicator/strategy. This is expected and has always been the case and is by design. We have advised developers of this in the past but in further research, I see this critical point should have been clearly documented and it will be going forward.

Here are a few points of clarification:

- OnMarketData() is guaranteed to be called in the correct sequence for all level I market data events received from the underlying data source (no data is ever dropped)
- e.MarketDataType determines what data type (bid, ask, last etc�) changed and triggered the call to OnMarketData()
- You should store local variables and update them as OnMarketData() is fired based off the data type that was changed
- e.MarketData can be ignored (if doing comparisons) since values can and likely will be ahead of the data type/value that triggered OnMarketData()
- This is because the underlying MarketData object can be updated on different threads and reflects the most recent values received (you of course will get a OnMarketData() call for these events subsequently)
- And as I replied to you before, FirstTickOfBar is only relevant in the scope of OnBarUpdate()

Ray

Jigsaw Trading · January 19th, 2011, 12:48 AM

Many thanks to the OP on this.

I noticed yesterday that something wasn't right on the ES. I have a couple of tools & one of them uses e.MarketData.Bid.Price;

I have been scratching my head all morning looking at code that should work - now I know why it doesn't.

Testing tonight - but based on the symptoms in the OP - this fits my problem perfectly.

DT

November 11th, 2012, 10:08 PM

Did NT fix this?

I haven't encountered this problem (yet), but perhaps this would increase smoothness:

Code

protected override void OnMarketData(MarketDataEventArgs e){

      MarketDataEventArgs L1DataEvents = e;

      if (L1DataEvents.MarketDataType == MarketDataType.Ask)newAsk = L1DataEvents.Price;

...

}

NinjaTrader · November 12th, 2012, 09:39 AM

grimReaper

Did NT fix this?

I haven't encountered this problem (yet), but perhaps this would increase smoothness:

Code

protected override void OnMarketData(MarketDataEventArgs e){

      MarketDataEventArgs L1DataEvents = e;

      if (L1DataEvents.MarketDataType == MarketDataType.Ask)newAsk = L1DataEvents.Price;

...

}

On post #14 I clarified the architecture and how to properly handle on market data comparisons in an asynchronous environment. There was nothing to fix.

June 1st, 2017, 08:37 AM

hi has anyone fix this as I'm trying to make an Indicator that will let me see the sales in the candle

June 5th, 2017, 09:53 AM

lance80

hi has anyone fix this as I'm trying to make an Indicator that will let me see the sales in the candle

Hey lance80

Have you checked out NT8 downloads?
There are several that will show you orderflow/footprint [" the sales in the candle" ] ie;
https://nexusfi.com/local_links_sort.php?catid=27&filter=&sort=d&page=1&pp=10&keyid=1210

Good luck

NT Providing Bad Price & Volume Data in OnMarketData!!!

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NT Providing Bad Price & Volume Data in OnMarketData!!!