Football players born in the first quarter of the year are most likely to be successful in the NFL, says new study
The study looked at 18,898 football players born after 1940 and found an excess of January and February births
Successful football players are ‘disproportionately’ born in January and February and, to a lesser extent, in March, according to a fascinating study in which researchers attempted to answer the question if the month an individual is born in can increase a person’s chances of playing in American professional football.
Researchers from Dartmouth College, New Hampshire, found evidence that players born in the first quarter of the year are more likely to play in the National Football League (NFL). The findings have been published in De Gruyter’s Journal of Quantitative Analysis in Sports.
Age is a critical determinant of success in sports and other domains of competition. Previous studies have demonstrated that children, who are born earlier in the year, may develop more quickly than their younger counterparts, with higher participation in sports, for example, as compared to those who are born towards the year-end.
This is known as the “relative age effect”.
For example, a previous study showed that there is a plethora of January births and a dearth of December births among North American professional hockey players.
While the importance of relative age across various sports is well-documented, it has not been studied closely in American pro football.
Accordingly, to investigate and document the matter of relative age effects among these athletes, researchers at Dartmouth looked at data on 18,898 football players from the National Football League, whose birth years ranged from 1940 to 1996.
Comparing the distribution of player births with births from the general population, the researchers found proof that NFL players are more disproportionately born in the early months of the year.
This, according to the research team, indicated that developmental advantages which relatively older players have in childhood carry into adolescence and impact individuals’ abilities to become professional athletes as young adults.
NFL teams consist of 53 active players, and the league conducts a ‘draft’ every April. Players enter the NFL both through this draft, consisting of roughly 260 picks, as well as through a post-draft signing period for undrafted free agents.
“We have shown with a collection of 18,898 American football players that professional success in football is associated with relative age. A practical implication of our results is that football talent evaluators should recognize that relatively older players within a given year cohort are better bets, all things equal, to be successful NFL players. Put another way, when NFL teams plan their draft strategies, they should take relative age into account,” said the paper.
The study says that, unlike in hockey or basketball, where systems of elite junior travel teams tend to dominate the high-level amateur competition, football runs almost entirely through local education systems.
Players who are successful at their high school programs proceed to college football, and the most talented players continue from there to the NFL.
Researchers said that while some communities have youth football programs, which function outside local education systems, such programs exist only as an option for players younger than high school age, and they “fade in importance” as players grow older.
Accordingly, said the researchers, a second potential source of age effects in football has its origins in the fact that pre-professional football in the US is often administered through local education systems.
“Age effects in football may be confounded by school cut-off dates, that is, dates that determine a child’s school cohort and, to the extent that a football league is affiliated with a school, affect when a child is eligible to play football. In a school with a cut-off date of, say, October 1, the youngest students will be those born in September, and we call an age effect associated with a school cut-off a school-based age effect,” said the paper.
Accordingly, the authors analyzed whether cut-off dates used by players’ school districts have led to relative age effects.
Their research showed that, in cases where players attended public high school in the US, and the cut-off date used in their state could be confirmed, a disproportionate number of NFL players were born in the fall months.
This is consistent with what the authors call a “school-based relative age effect”.
“From the perspective of players, our findings imply that one’s school district, and potentially one’s position, are not negligible factors in determining success,” the findings state.