Perspectives on Probability

by Ben Perreira

The gentleman I worked for a few years ago whom I referenced in my very first post of this blog once told me, “You learn a lot more about someone in one bad day than in 1000 good days.”

NNT refers to a similar concept in The Black Swan, through a graph that show the life of a turkey abruptly ending on day 1000 (presumably a couple weeks before Thanksgiving).

The underlying logic behind a focus on prediction through routine, though flawed, is tempting: something has happened in the past so consistently is extremely likely to happen again to the point that planning for contingencies would be a burden.

In controlled circumstances, it’s a different story.

I had a conversation with a friend about blackjack the other night. I am not a blackjack player so I could be wrong here, but our discussion hinged on how other players in the game affect your odds based on when they hit or stay. My friend held that he could justifiably blame a fellow player for being a poor player and hitting at the wrong time if it meant my friend got the “wrong” card by playing the right way. I tried my best to understand the logic, but it didn’t add up.

The other player’s decision to hit or stay would certainly affect my friend’s chances in that one hand, but by definition of randomness and probability in cards, the other player could not affect him disproportionately toward a positive or negative result in the long run. Thus, if he gets mad at the guy for hitting at the wrong time and it causes him to lose, he better give the same guy a tip when he hits at the wrong time and causes my friend to win big.

The point: we like to use statistics and probability, but only when they work in our favor. Probabilities in our favor reinforce laziness, while probabilities not in our favor can be written off as anomalous.

For example, let’s say the odds of meeting one’s dream mate today are 1/1000, the same odds as a good person turning bad from the example above. We are more likely to see the odds of a good person turning bad as negligent than we are to see the low odds of meeting a dream mate as hopelessly low.

Do our minds trick us into being optimistic as a defense mechanism? Or are some other forces at work here?