I'm trying to work out what % component of my stock movements are just general market movements. I would like to know I have some % advantage over the general market. Since I only have the day of entry and exit for each trade I'm trying to work out the best level to record for the market index for analysing my past results, would it just be L+H/2 for an average price? Or perhaps there is a more commonly accepted average price measure for OHLC daily bars. Does anybody else measure their unleveraged stock picking skills vs general market drift? I have read that 70% of a stocks moves are just a result of the overall market, though I haven't seen any data to back up these claims.