As a strategic asset allocator, I don't believe in timing markets, and agree with the conclusion of the analysis. However, the manner in which we get to the conclusion seems flawed. Of course if you miss only positive weeks you are going to hinder performance. The likelihood of timing being that perfect to only get out and then back in exactly when positive weeks occurred seems implausible at best. I have seen a couple of marketing pieces which give the opposite analysis suggesting if you can miss the worst days you are better off the classic "win by not losing" mentality.

The real question one needs to ask themselves is "do they believe they can miss more bad days than good?" If so then the math will be positively in their favor, if not it will be a hindrance to long term performance.