Volume label incorrect?

[GenSpoo]

I'm sitting here watching the value of the volume label on my NQ chart. Trades are going off that I can see in a ticker and another data feed. My volume label doesn't move most of the time. Why? It does occasionally and in spurts, and I am getting a volume histogram, but it sure doesn't seem to be paying much attention to the real-time executions. Am I missing something? Shouldn't it increase by the same number of contracts that trade in real-time?

[AndyS]

Hi GenSpoo,

Thank you for posting this question. I want to confirm that I see what you are seeing and have sent this over to our engineers for their review. At this time I don't know if this is an actual bug or if they use a different method in collecting and displaying the trades in the Volume Histogram of an Advanced Chart.

When I know more I'll post an answer here.

Thanks,
Andy

[brianb]

I noticed this back in 7.1 and talked to rep about it, he said I was having packet loss, wrong answer.
A friend and I both monitored the same symbols and we both saw this many times over many days. I gave up on it since the histogram was a visual representation and deemed accurate enough for my needs. However it still bugs me that it isn't accurate.

What I can suggest is that if you want a more accurate total for each bar open a seperate basic Interval Tabular chart. Yes I know this type of chart is a pain in the you know what and a non field adjustable spacehog (hint please fix this) , but you may be surprised to see the difference between the histogram # and the basic chart # be as much as 6%. I know I have. Although many times it is right on the money. I suppose it varies according to a dozen or so variables each time. Hope this helps.

Brian

[GenSpoo]

I think I just realized what the problem is. Apparently the charts only trigger a redraw of data when the open, close, high, or low of the price bar changes. So if volume is coming in, but all at the same price, the volume histogram won't display it until the price changes. I can only assume it still counts the volume for later dispaly (I sure hope).

If this is the case, I would like to request that it should be possible to update the volume histogram even if price doesn't change, as it is critical to see the volume flowing in.

[GenSpoo]

And, if it is true that it is only displaying updated volume if the close of the bar changes, then we need to make sure that if the bar closes at the same price it opens (for example) that when the new bar starts, the previous bars volume updates. Not sure I said that clearly. For example, that last 20 ticks of a 5 min bar are all the same price. A new bar starts. Did the last 20 ticks of volume get displayed in the previous bar since the price didn't change prior to closing?