Looking through the Twins’ active roster after yesterday’s string of cuts, an unusual trend struck me: of the 32 men on the active roster, five have a birthday in December.
Now, a group of 32 people having a month with five people may not be particularly anomalous given the randomness inherent in populations, but that month being December struck me. I have a December birthday, and growing up in a small school, I was often the only student in my class to have a birthday in the final month of the year. We had a lot of November birthdays, unsurprising since that correlates to conception on or around Valentine’s Day, but never many in December.
So while this can almost certainly be explained by statistical randomness, it should also be noted that December isn’t even the most common birthday month on the roster. Along with the five December birthdays, five players have birthdays in March, and seven were born in August. That’s over half the roster accounting for just three months in the year.
Is this anything more than statistical randomness? Not at all. But it has made me wonder if future parents of baseball players decide to copulate around the MLB calendar:
…Alternately, it’s just statistics.
One more note when it comes to statistics and birthdays: any mathematician seeing those words in conjunction will immediately think of the birthday paradox.
For those unfamiliar, the birthday paradox states that it only takes 23 people in a group of to have a 50 percent chance of any two of that group sharing a birthday. An active MLB roster is 26, so the chance is slightly more, and that chance increases further with the 32-man roster the Twins currently have for spring training.
As it turns out, there is not just one pair of players with matching birthdays, there are two, and it’s pretty likely all four players make the initial roster:
Alas for me, despite the several December birthdays, none of the five players shares my birthday. And on another personal note, across MLB history, no player has ever had my exact birthday (month, day, and year); since I’m in my 30s, it’s safe to say that none ever will. (There has been an NFL player whom I share an exact birthday with, though he is no longer active.)
Anyhow, as the roster gets trimmed and changed over the course of the season, we’ll see how many of these birthday patterns change. Statistics!
(And not “advanced statistics” like John Smoltz and his ilk love to gripe about. Probability!)