Relative Age Effect
Is there a relative age effect in cricket?
The relative age effect is the phenomenon where children born early for their age-level cohort are over-represented among elite performers in later life. A recent Cricinfo article studied its impact on cricket by analysing the birth dates of two England Under-19 squads. To impart more rigour to these findings, I scraped player data from all Under-19 World Cups and Australian Men’s Internationals between 2007 and 2020.
The age-group birthday cutoff is September 1 for junior cricket in Australia, New Zealand and England. There is clear evidence of the relative age effect: whereas you would expect 33.4% of players to be born between September and December1, these countries have had 62.8%, 59.8% and 39.1% respectively.
Even more disheartening is the flow-on effect at senior level. The relative age effect has been just as strong in the Australian Senior Men’s team as the Under-19 squad.
How many potential greats have been lost to cricket before their tenth birthday?
I used Python’s BeautifulSoup, pandas and Plotly libraries for the web scraping, data manipulation and visualisations respectively. Check out the Jupyter notebook here.
1 Well, almost. The Journal of Human Reproduction seems to be an authority on such questions.