All that being said, I do see empirical work out there that links past returns to future ones. Very often, these studies find value and momentum effects (circumstances in which past returns lead to reversals or continuation) that are tested for economic as well as statistical significance. I have also seen traders firmly define patterns that "set up" in intraday markets and test them out for skews in forward returns, creating successful "playbooks" that guide their trading. This study of market intraday momentum recently came to my attention as an example of more rigorous implementation of price patterns as potential predictors. I also observed a daytrader this past week rigorously test a pattern of behavior in the VWAP of stocks that led to short-term momentum.