from Amazon
Friday, April 18, 2008
Not EXACTLY one run, but AT LEAST one run
Smart people make this mistake all the time, but friend-of-The-Book Joe Sheehan doesn’t:
...with a runner on second and no one out, you have a 62.5% chance of scoring one run. With a runner on third and no one out, you have an 82.7% chance of scoring one run. With one out and no one on, you have a 16.5% chance of scoring one run
He references BBTN, and we have it in The Book as well, but, I’ve also got it online right here. While he did say “one run”, he really meant “at least one run” and not “exactly one run”. And his numbers bear that out. And he was right to compute it that way. With one out and no one on, the chance of scoring exactly one run is 10%. But, the chance of not scoring at all is 83%, meaning the chance of scoring at least one run is 17%. And that is the number we care about. Invariably, we almost always want to know chance of scoring not at all, or its complement. (His 82.7% for runner on 3B looks mighty low. I have it at 86.4 for 1999-2002. Did he mean to say 87.2%?)
Good job to Joe in not falling into the trap. Admiral Ackbar has snagged many a fine folk.