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This article originally appeared in ETF.COM here.

As expert poker player Annie Duke explains in her book, Thinking in Bets, one of the more common mistakes amateurs make is the tendency to equate the quality of a decision with the quality of its outcome. Poker players call this trait “resulting.”

In my own book, “Investment Mistakes Even Smart Investors Make and How to Avoid Them,” I describe this mistake as confusing before-the-fact strategy with after-the-fact outcome. In either case, it is often caused by hindsight bias: the tendency, after an outcome is known, to see it as virtually inevitable.

Duke explains: “When we say ‘I should have known that would happen,’ or, ‘I should have seen it coming,’ we are succumbing to hindsight bias.” She adds that we tend to link results with decisions even though it is easy to point out indisputable examples where the relationship between decisions and results isn’t so perfectly correlated.

For example, she writes, “No sober person thinks getting home safely after driving drunk reflects a good decision or good driving ability.” The lesson, as Duke explains, is that we aren’t wrong just because things didn’t work out, and we aren’t right just because they turned out well.

Don’t judge performance by results

“Fooled by Randomness” author Nassim Nicholas Taleb put it this way: “One cannot judge a performance in any given field by the results, but by the costs of the alternative (i.e., if history played out in a different way). Such substitute courses of events are called alternative histories. Clearly the quality of a decision cannot be solely judged based on its outcome, but such a point seems to be voiced only by people who fail (those who succeed attribute their success to the quality of their decision).”