New filter?

After bouncing some thoughts off a buddy of mine, it got me considering another potential filter for the stocks i trade.

In a nutshell, certain sectors/stocks will lead the index. So i should be looking to those leaders or laggards for my trades as they would likely be the ones that are 'moving independently' and should comply with proper analysis. The alternative are other stocks, the 75% that move 'with' the index, and would likely be wafting around.