I am using a one-minute chart with Volume Bars on the chart.  I noticed that the "Edit Volume Window" allows one to select by checking "Truncate volume spikes > X average volume."

The black box problem is that a user doesn't know what value is programmed in for "average volume".

Can you provide any insight as to the value for average volume on a one-minute chart?

In v7, it was based on the visible volume bars on the chart. I would have to do some testing to see if it is the same in v18 or not.

Based on my testing, it seems to use the entire available history on the chart to calculate the average volume (so usually about 500 bars or so). This average is then applied retroactively to all of the available volume bars.

I would think that if it were for one whole day the calculation would be 6.5 hours * 60 minutes per hour = 390 minutes.  Am I wrong? 

Also, are one-minute Volume Bars with less volume than 100 show up as hyphens on the one-minute chart.  Are these counted as part of the possible 390 bars (or as you say the approximately 500 bars)?

There could be up to 890 x 1-minute bars on the chart by the end of the trading day for a stock. It would start the trading day with 500 and then add 390 news bars throughout the trading day.

All of the bars seem to count, including the bars without any volume. This is if my experiments are actually indicating what they seem to be indicating.

So you're saying the number of volume bars in "the average" accumulate as the day continues on. 

I can plot the one minute volume bar as a column and watch it change from one minute to the next minute.  No problem there.

However, my ideal would be a column next to that one minute volume bar that would show me when "the accumulating average volume" is three times the average volume (truncated).

Can you imagine any way to do this?

No, I cannot think of any way to calculate this for display in a WatchList column.

Let's continue to consider this problem by moving to a Daily chart of RARX at the close of the trading day.

The EOD Daily Volume for RARX printed as 13,600. 

By twice plotting Volume bars on the chart, one can see that this Average Daily show truncation at 5X, but no truncation at 6X.

Therefore, the approximate Average Daily Volume could be greater than or equal to 13,600/5 = 2,720...and less than 13,600/6 = 2,267 (rounded to two decimals).

It you agree with this, then can you calculate how many days would be included in the formula for Average Daily Volume?

There isn't any settings for this besides truncating or not and the multiple of average volume to truncate. There is no period setting.

On a daily chart, the period for the calcualtions of a symbal which has been around that long is 500 before the trading day starts and 501 once the trading day starts because that is how many bars are on the chart.

So:

AVGV500

Or:

AVGV501

Please disregard what I said in the message directly above this one.

I apologize for the confusion as I was looking at the EOD One-Minute Volume, not the Daily Volume.

Now RARX at 13,700 (greater than 13,600 a couple minutes ago), One Minute Volume could be greater than or equal to 13,600/5 = 2,720...and less than 13,600/6 = 2,267 (rounded to two decimals).

If you agree with this, then can you now calculate how many minutes would be included in the formula for Average One Minute Volume?

The Daily Volume for RARX is printed at 508,100.  If Average One Minute Volume is 2,720 or more, let's divide 508,100 by 2,720 suggesting 186.80 minutes, less than 390 or 500+390.

What do you make of this, Bruce?

The number of minutes used in the calculation seems to vary throughout the day because the number of minutes available in the chart vary throughout the trading day. As far as I can tell, it is using all 890 bars on the 1-minute chart to calculate the average volume currently.

Look at RARX on a 1-minute chart (your example) and set the Truncate volume spikes > to 16 times avg volume. At this point, you will stop getting truncated volume bars.

Now plot the following Custom PCF Indicator in the same pane and scale as Volume.

You should see why I think it is just using the number of bars on the chart.

Yes, on RARX I see this creates a horizontal line to the right as one as one uses Price History as the Data Source.   Is this what one is supposed to see on the Custom PCF Indicator plot?

However, If one uses Volume as the Data Source, as you've suggested, then no horizontal line appears to the right.

You aren't supposed to change the data source to volume (that won't work at all with Custom PCF Indicators). You are supposed to scale the Custom PCF Indicator with Volume.

Right-click on the name of the Custom PCF Indicator at the top of the pane in which it is plotted and select Scaling. Then make sure it is scaled with Volume.

Note that tere won't be enough data available to plot 16 * AVGV890 in a 1-minute time frame since it reset to 500 and started counting back up for today.