Two no-hitters four days apart is not that rare

Justin Verlander just threw a no-hitter for the Detroit Tigers. On May 3rd, Francisco Liriano threw one for the Minnesota Twins.

There have only been 271 no-hitters in one hundred years of Major League Baseball, so two separated by four days seems unusual.

But two no-hitters within four days of each other has happened several times before. From Wikipedia, there have been two no-hitters within four days of each other on the following dates:

August 19 and 20, 1880
September 19 and 20, 1882
two on April 22, 1898
September 18 and 20, 1908
August 26 and 30, 1916
May 2, 5, and 6, 1917
September 4 and 7, 1923
June 11 and 15, 1938
June 26 and 30, 1962
September 17 and 18, 1968
September 26 and 29, 1983
June 1 and 2, 1990
two on June 29, 1990
September 4 and 8, 1993
May 11 and 14, 1996

Is this list surprisingly long? If you assume that baseball has been played 180 days a year for 130 years, then that's 23,400 days on which baseball has been played. There have been 271 no-hitters, so on an average baseball-playing day there are 0.01158 no-hitters. After any given no-hitter there's a four-day window in which the list I gave above could be added to. So you'd expect (271)(0.01158)(4) = 12.5 pairs in that list. There are 17 pairs on the list. (I'm counting the 1917 triplet as three pairs. I'm not counting today's no-hitter.) So there doesn't seem to be particularly strong evidence for no-hitters somehow causing more no-hitters in their wake. (Although my model of the baseball schedule is, I admit, ridiculously crude. In particular I have ignored the fact that the number of teams isn't constant.)

Phillies radio silliness

There's a commercial which airs on Phillies radio broadcasts. Since I dislike Comcast, but am addicted to the Internet, I'm willing to pay them for high-speed Internet access but not for cable TV. This means I listen to Phillies games on the radio.

Anyway, there's a commercial for Citizens Bank (who own the naming rights to Citizens Bank Park, where the Phillies play) that regularly airs during these broadcasts. It goes something like this (I'm paraphrasing, but the "math" is correct):

Did you ever notice how important the number seven is to the Phillies? They've won seven National League East division titles. There are seven letters in Ashburn, Schmidt, and Carlton. Thirty-two Hall of Famers played for the Phillies. Divide by the number of runs scored in a grand slam and, yes, you get eight. Subtract the number on Whitey's back and what do you get. Seven!

The voice then proceeds to tell us how Citizens Bank is open seven days a week. Which I suppose would be nice to know if I didn't do basically all my banking at ATMs anyway.

But I think the commercial is intended to make fun of people who jump through hoops like this to make the numbers work out. And seven is a small number and therefore easy to manufacture by the manipulation of other small numbers, or so I noted on July 7, 2007.