It's is possible to chekc the sustainable competitive advantage with quantitative analysis. AAPL and DELL example.

Read the full article: http://goldstockanalyst.net/?p=7

Here you can read how stock prices and actual competitive advantages are uncorrelated and how I checked the SCA (Sustainable competitive advantage) with quantitative tools.

Vested Interest: 
I own the shares of DELL, sold AAPL for short recently.