Yes or No or Neither

If someone says to me “I think the Yankees will defeat the Red Sox” or “I think Obama will be reelected” I don’t know what to think. Or, more precisely, I don’t know what they mean, and I don’t think they do either.

Yesterday, I watched a variety of golf pundits bandy about percentage chances of Tiger Woods surpassing Jack Nicklaus’ 18 Major Championship record (30% to 50%). Two years ago, if you asked just about any golf guy the same question,  they considered it a foregone conclusion that Tiger would beat it, and perhaps by many.

What does the above say about the golf pundits? One might defend them by saying “with the available information, the conviction they held two years ago was justified.” To which one might respond “without all the facts, they had no business prognosticating with such certainty.” But what of these 30 and 50 percent guesses?

Does a 30% guess meaningfully translate to: “I do not think he will?” One might make the argument that any estimate of anything that falls below 50% means I don’t think so and any guess above 50% means Yes, I think so. Then again, one might argue that outside the world of bookmaking, humans demonstrate a very vague relationship with probability.

10% – Not very likely but more than technically possible.

20% – I won’t be shocked, but would would feel hard done by if I was betting against it.

30% – A solid chance, but not very likely.

40% – Might as well be 50-50 for all I know. Worse than a coin flip, but only just.

50% – A coin flip.

60% – Might as well be 50-50 for all I know. Better than a coin flip, but only just.

70% – Its pretty likely, but don’t bet the farm.

80% – Still don’t bet the farm, but bet heavily and feel wounded if it goes against you.

90% – It’s practically a lock.

The above is my personal vague relationship with numbers. I do my best to struggle against those instincts, but am nonetheless subject to my guts and what they think about probability. The reason I fight against my intestinal conviction is the simple and obvious fact that things that happen ten percent of the time happen… ten percent of the time. ‘Ten percent’ doesn’t imply anything other than ‘not some other percentage.’ Yet, I, and by my experience just about everybody else, heap all kinds of implications upon the bare facts of probability.

Contextually, probabilities do take on all kinds of meaning. If someone offers you a one in ten chance at a million bucks for a buck, and you can afford to lose the buck, you take it. If they offer you a one in one million and one chance at a million bucks, you decline. Not because one in ten is “reasonably likely” and not because one in a million and one is “astronomically unlikely” but because a buck and million bucks, and 1 in 10 and 1 in 1000 001, have a mathematical relationship that proves  if you play the first game you stand to win in the long run, and in the second, you don’t. Put another way, it is possible to make a bet that wins 99% of the time, and have the bet be wrong. If you bet a thousand dollars to win a dollar on the spin of a 100 space wheel that contains only one losing space, you’re an idiot.

However, it might be completely impossible to manage life without some kind of instinctual, if vague and bizarre and perhaps very silly, relationship with probability. If there is a 70% chance I will die if I go on vacation to Cambodia, then I am not going to go. If there is a 1% chance, then I might. Most of us will have a similar reaction to similar circumstances, but there is no logic being applied to the vacation decision other than 1% is lower than 70%. Why is 1% low enough? Would 2% be too high? 5%? Why not 0.5% as the threshold?

The other day in Slate there appeared an article estimating Sarah Palin’s chance at running for president at 40%. What does that even mean?

Robin Lindsay



Tags: , , ,

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: