I think the exercise of trying to figure out how to simplify concepts has been incredibly helpful to me over the last 13 years of teaching and I hope my students have benefited from it.

Here is part of the tradeoff with diversification. You must be diversified enough to survive bad times or bad luck so that skill and good process can have the chance to pay off over the long term.

There's a clarity that comes with great ideas: You can [easily and simply] explain why something's a great business, how and why it's cheap, why it's cheap for temporary reasons and how, on a normal basis, it should be trading at a much higher level. You're never sitting there on the 40th page of your spreadsheet, as Buffett would say, agonizing over whether you should buy or not.

If I plug my estimates into the Magic Formula, and it comes out cheap, that's good.

It just seems logical that sticking to investing in only a small number of companies that you understand well, rather than moving down the list to your thirtieth or fiftieth favorite pick, would create a much greater potential to earn above-average investment returns.

Figure out what something is worth and pay a lot less.

The big picture is: the main thing you should be concerned about in the future are incremental returns on capital going forward. As it turns out, past history of a good return on capital is a good proxy for this but obviously not foolproof. I think this is an area where thoughtful analysis can add value to any simple ranking/screening strategy such as the magic formula. When doing in depth analysis of companies, I care very much about long term earnings power, not necessarily so much about the volatility of that earnings power but about my certainty of "normal" earnings power over time.