You can look it up, but the simplest way, sufficiently accurate, is to assume that the volume for a green bar was all market longs and the volume for a red bar was all market shorts. You multiply the volume by the average of the high and the low, applying the appropriate sign for the bar color, add it to the same product for the previous bar, and divide by the cumulative volume, continually iterating after each bar closes. Be advised, however, that although it is a pretty study, it is totally useless. That is why I use it so much. And you're not fooling me a bit, 22, you will always be a small calibre, in trading, in life, and in the bed.