Why I'm not a professional sportsperson, maybe?

Following up on yesterday’s deep dive into NBA birthdays I’ve been reading more about the relative age effect. This is the apparent phenomena whereby “older” players are over represented in professional sports. By older I mean that professional athletes are more likely to be born at the beginning of the year.

There’s actually a remarkable amount of research on this phenomena, and it appears to hold for some sports, in some countries, especially in Europe. One paper notes:

During the last three decades, researchers have identified overrepresentations of athletes born in the first quartile of the selection year (i.e. January to March if the cut-off date is 1 January) across cultural contexts in sports such as football, ice hockey, handball, baseball, basketball, rugby, volleyball, tennis, ski sports and swimming, Till et al.. demonstrated the possible extent of such over representations of relatively older players in rugby: 47.0 % of the regional and 55.7 % of the national junior representative players were born in the first 3 months of the selection year

It does not appear to hold for the NBA, as I discovered yesterday. That basketball finding was in France. And many of these studies found the phenomena reduces with age. It’s more prevalent in teams of teenagers than the higher grades, for instance.

But what about cricket? Again, a thought that hit me today as I was planning attending some upcoming test matches. One study of Australian cricket players again found no significant difference in relative age among state level players, but did for lower grades.

Players born in the first quartile of the cricket season were significantly over- represented in both male Under-15, Under-17, Under-19 and female Under-15 and Under-18 levels. However, there was no significant difference at the senior state level for either male or female cricketers.

What about Sri Lanka? Where schools play an outsized role in player development and the club system is a mess. I haven’t been able to find research on this so I decided to scrape the birthdays for all 150 Sri Lankan test players from Wikipedia:


Not much to go on here. Not much of a difference. And not enough data points to say the variation is much more than randomness. I may try to find a larger database of Sri Lankan club players.

But, have I been cursed for my October birth? It seems to depend on a lot. Given I grew up in Australia probably not.