Performance Perspectives Blog

“Logic does not require empirical verification”

by | Aug 23, 2010

The above quote comes from Nassim Taleb’s Fooled by Randomness, which I started to read over the weekend while vacationing at the Jersey Shore (light reading). I’m finding that the book, as with his later Black Swans, has many interesting insights.

But this quote, to me, says a lot.

When, for example, I discuss the topic of money- vs. time-weighting, I often resort to logic (or at least to me it’s logical). If we use time-weighting to eliminate the impact of cash flows because the client controls the flows, then wouldn’t it seem logical that we would include the impact of cash flows when the client doesn’t control the flows (i.e., when the manager does)? To some it apparently doesn’t seem logical; in fact, some argue that you cannot use this form of logic. That yes, it is true that we use time-weighting to eliminate the impact of flows when the client controls them, but when the manager does we should still use time-weighting.

Sorry, this doesn’t seem logical to me. If anything┬áthis counter argument screams the absence of any logic.

Fortunately, there’s plenty of empirical evidence to demonstrate why money-weighting is the way to go when the manager controls the flows, but to some no amount of evidence will sway their view. Oh, well. You win some, you lose some. The reality is there are different views and everyone is entitled to theirs.

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