Does anyone have any details about just how the IB data is sampled? I've been told this many times, and I'm sure it's true, I would just like to know what the sampling rules are.
Going back to the original, I have checked IB volume data against others. I did so in recently in a thread on T2W, I can' remember where. However, the IB Dax volume was an exact match in that case for the figures quoted for a number of other sources, tenfore was one, with the exception of MyTrack, which didn't match at all, and considerably undereported.
So I would assume that even if IB is only sending us a sample it is presumably sending out the correct total volume for each time sample, so the end volume result is correct.