The NFC won the coin toss in the Superbowl tonight. The commentators were quick to announce that the NFC has won 13 years in a row, at odds of greater than 8100 to 1.

The pre-test probability of tonight's result was 0.5 (1 to 1; 50%). The post test probability is 1.0 (100%). My point:

It is meaningless to speak of a series of past events in terms of probabilities as if the events had not yet occurred. Someone might opine that the odds of someone named Flitzerbiest, typing a message on probabilities with right-hand dominance from somewhere in rural Minnesota must be millions to one. This fallacy is that these things have already occurred, and probability is therefore irrelevant.

And, speaking of relevance, it was this sort of shoddy presentation of probability, which I first encountered in Josh McDowell's Evidence that Demands a Verdict which led me, as an aspiring Christian apologist, to suspect that the evidentiary case for Christianity was actually quite weak indeed. The rest, as they say, is history, the odds of which are 100%.

I agree. Most of us normal human beings don't get probability at all, and are often completely baffled by simple stuff (if there are 26 people in a room, the odds are slightly better than half that two of them will share a birthday!)

It's like an ad I've seen on TV recently, with a couple of actuaries discussing the odds of various things happening on the street in front of them. Suddenly, a man riding an ostrich goes by - and one of them asks the other, "what are the chances of that?" And the second, wisely answers, "100% --- NOW."

Sorry you had a tough night, Eric. Join the rest of us in waiting for next year.

I had a tough night two weeks ago.

I thought you were an Indy fan or was that your son?

Vikings.

So, there was never a reason for me to dislike you? I've been harboring all this resentment for nothing?

No, that's not true. This really is my own hair...

Right, I forgot about that, you &*$%#* ^%&%$$# @%$()#%* !!

Reminds me of a parable aimed at reinforcing the concept of independence. The odds of getting on a plane that has on it a passenger with a bomb are pretty slim. Moreover, the odds of getting on a place that has on it two passengers with bombs are even slimmer. So based on that, someone brings their own bomb, as that will make the odds of someone else on the plane with a bomb very slim.


There is another, related, fallacy that correlation implies causation automatically.