Can anyone explain the difference btwn advance/decline & up volume/down volume?

Advancing issues are the stocks trading in positive territory from yesterday's close. Decliners are negative for the day, at that point in time. You would expect to see more advancing stocks than decliners on the NYSE, on an up day in the Dow. But let's say the Dow is up 100 pts, but there are just barely a few more advancers than decliners, or the decliners are more than advancers. This is referred to a "divergence." It signals that the broad market is not following the Dow, and that Large Cap stocks are outperforming the Small Caps.

Up volume is that volume that exchanged hands on an up-tick in price. Down volume was exchanged on a down tick in price. The On Balance Volume indicator uses this relationship to build a chart showing various technical analysis indications. If a stock moved one point up on half the volume it took to go down one point, then the stock is probably being "put up" and not being "bid up."

Volume is more indicative by itself to me, than Up Volume. For price to continue rising, volume should be rising or above average. This relationship holds always for me. Up Volume is just an occasional descrepancy, and supplies little confirming or additional information.

1

Decline and Advanced is the number of stocks that went down or went up. It has nothing to do with volume. You could have nine low volume stocks go down and one high volume stock go up, and advance to decline is 1 to 10 -- but up volume could be huge.

yes this dynamic is known as The Arms Index and also as TRIN, look either up for some detailed info.