If you’re a hockey fan and haven’t read Malcolm Gladwell’s Outliers yet, I’d suggest picking up a copy (or at least settling into a nice chair at the bookstore and reading the first chapter). In the first chapter,  Gladwell convincingly drives home the point that minor league hockey suffers from the Matthew Effect. Basically, the closer a player is borng to January 1st, the date Canadian hockey uses to divide age groups (atom, pewee, bantam and midget), the more likely you are to play at a higher level. The reason is fairly simple. When kids are trying out for top tier teams, the ones born in January are almost a full year older than the ones born in December. At 9 or 10 years old, a year can make a big difference in terms of size and coordination leaving younger players more likely to get cut. Even as the players age and the difference between the January and December babies gets smaller, those that have already played on top tier teams have much more practice and competitive hockey experience under their belt. The result is that an initial difference in size and coordination due to a player’s date of birth can have a huge impact on who makes it to the big leagues. Gladwell even suggests that international hockey organizations could double the pool of elite players they have to choose from simply by taking the Matthew Effect into account when designing their hockey development programs.

I decided to dig up one of the studies Gladwell mentions in the book to see if the effect was as strong as he said. This 1988 study done by Barnsley and Thompson looked at the birth date of over 7000 minor league hockey players in Edmonton.  As Barnsley himself says in the book, forget about the stats, these graphs speak for themselves. The top graph compares the number of players expected in each quarter of the year (three month periods) to how many players they found. It’s a little bit exaggerated because of the scale (it only goes from 1600 to 2000) but it’s clear that there are many more players with birth dates in the first half of the year than the second half. The second graph (right) shows a clear relationship between when a player is born and the level they play at. Nearly 40% of the top tier hockey players were born in the first three months of the year while only 12-13% of top tier players were born in the last three months. When a player is born clearly affects where he or she ends up playing. You can find a link to the full paper below.

I also looked quickly at the birth dates of the Canadiens, hoping I could blame this year’s poor showing so far on the luck of the birthing draw. Unfortunately, we don’t have more players born later in the year than other teams. In fact, over one third of the first place Penguins’ roster is born in July, August and September including their four top scorers: Crosby, Malkin, Goligoski and Kunitz. Riddle me that one Gladwell.

Here’s an interesting interview ESPN did with Gladwell about this effect including a tally of all NHL players born between 1980 and 1990. Wouldn’t ya know it. Gladwell was right.

Reference: Barnsley RH, Thompson AH 1988. Birthdate and success in minor hockey: The key to the NHL. The Canadian Journal of Behavioural Sciences 20(2) : 167-176