Hi Paul,

Thank you for your comments and for the link to the paper.

The paper that you highlight and that gained attention via Mauboussin's book is exactly why I wrote the post. Even more importantly, the reason I developed the technology I discuss above in the post is because as a fund manager I wanted to absolutely have a way of ensuring that I could develop skill so that I would be able to separate skill from luck. If I record the reasons for my choices ex ante and then reality unfolds how I described it then I can be pretty sure that the performance I am logging is not due to luck. The study you quote above extracts its information from returns data, not from choice data. The distinction as I highlighted in my post is that only a very small subset of your choices are reflected in a portfolio.

Cheers!

Jason