Ok so I have noticed this since I started trading and always found it interesting. When I draw a trend line when it is hit their usually is alot of volume keep price action within the trend. So others are entering the market when I am entering. Since this is usually the biggest volume bars one must assume that we should follow this volume. The question on what came firts volume or price is not the right question to ask, but it would be wiser to ask why did volume come in a certain time. What are the majority of people trading? what indicator or what trend line. Is the volume coming in on a MA crossover ? or a trend line or what ever. Then go back in history a bit and see if it is consistent. Is the volume at these key times still holding up, or have people lost interest or accomplished their goal. I was watching Warren Buffet and when he was asked when he sold a certain stock. me responded by saying it was over 6 months. I imagine that every time he sold it would show some volume on the chart of the stock he sold. this would create traceable volume increases and one should be able to get an idea if he was selling at the same price each time (support resistance) or if he was doing so at increasing price levels (trend line) Also if we look carefully at high volume wide range bars we can see that these bars are very important as they represent selling or buying price initiation and limits. If some one is willing to buy in that range only, we may be able to back test and see if they will still buy at that level down the line. At worst it would be a good pace to put a stop.