CANADIAN HOCKEY

I know nothing about Canadian hockey.

Nothing except what I have read in two separate books now: a statistical mystery involving birthdays that ultimately had a simple explanation. 

A few years ago a researcher noticed something odd about the birth months of Canadian hockey players; from the top school age leagues to the NHL, the following trend was consistent:

40 % of the players were born in January, February or March.

30% were born in April, May or June.

20% were born in July, August or September.

And only 10% were born in October, November or December. 

The researcher scratched his head. Shouldn't we see an equal 25% of the birthdays falling in each of the quarters? Why so many first quarter birthdays and so few fourth quarter birthdays?

So ... any guesses as to the explanation?

It turns out to be very simple.

The competitive childhood leagues are ordered according to age and each league nationwide has the exact same cut off date for eligibility: January 1st.

This means that a young hockey enthusiast born on January 2nd is playing with other boys who were born later the same year. Mister January 2nd, in other words, has the advantage of three, six, nine or even nearly twelve months of physical development over the majority of his teammates. 

He's taller, stronger, and more coordinated than his younger teammates with October, November or December birthdays. The coaches are going to notice him, give him extra game time, and work him harder during practice. As a result, he will have a much better chance of advancing to the next level. He will become the better player. 

So the explanation of the predominance of January, February and March birthdays in the NHL is very simple.

But the ramifications of this observation about Canadian hockey are deep and complex. Consider how the cards can be stacked against someone based on some initial misfortune completely outside of his or her control - in this case, for example, a potential hockey star who has the bad luck of being born in December. It seems like it's more than hockey that works this way - it's life.