Wednesday, July 11, 2007

Streaks and All Stars

Have you noticed that no one calls the National League the senior league anymore? I guess despite being 25 years younger, after 106 years the American League’s stature is apparently equal. Or perhaps even greater: The AL won its tenth straight All Star game last night, beating the senior league 5 to 4. Gee, ten in a row. I wonder who will win next year…

If a coin is flipped and comes up heads ten times in a row, what would you bet on next time?

Some people say tails. These are the type of people who dump regular sums of money into casinos. When they’re winning, life is good. When they’re losing, they think their luck is bound to change. Alas, their luck never changes and their random walk will always eventually lead to ruin.

Other people say it doesn’t matter – it’s still 50/50. After all, it’s a coin and it doesn’t remember how it landed last time – or the last 10 times. And if you toss the coin often enough it’ll turn up heads 10 times in a row eventually.

The folks with the best understanding of probability and statistics would say heads. The reason? The odds that a coin will turn up all heads or all tails in ten consecutive tosses is 511 to one. The question that comes to mind is whether or not this coin is fair. Most people feel comfortable with 95% confidence about such a hypothesis. In this case we in fact can be 99.8% confident that the coin isn’t fair – it is biased towards landing heads.

All Star games, coin tosses, what’s the difference? Does that mean we can be 99.8% sure that the American League is better? Actually not. The difference is that there is a lot more history to the All Star game, and for example if we go back far enough we find that the National League won 11 games in a row starting in 1972.

And another stat that shows the teams are evenly matched: in the 77 All-Star games before last night the AL and NL each scored 326 runs.

So after ten years will old age and treachery finally outwit youth and skill? Stay tuned for next year’s All Star Game! But just don’t think it’s a lock bet.

No comments: