The Relative Age Effect and the Birthplace Effect in the National Football League

This dissertation, "The Relative Age Effect and the Birthplace Effect in the National Football League" by Po-tak, Cheung, 張溥德, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: The relative age effect and the birthplace effect in the National Football League - Cheung Po-tak (1995048736) Abstract Two contextual factors that have been suggested to influence the likeli- hood of an individual becoming an elite athlete are their relative age and the population size of the community in which they are born and raised. This thesis examines the existence of these factors amongst current National Football League (NFL) players. The first part of this thesis concerns the relative age effect, which is the advantage enjoyed by athletes born earlier in the year, thus being relatively older than other athletes born in the same year (Musch and Grondin, 2001). Previous studies have shown that the relative age effect is weak, or even non-existent, among American Football players. While the data for the players as a whole sug- gests that this is the case, a breakdown of the data according to the players' posi- tions may present us with a new perspective. By looking at the relative age ef- fect on a positional basis, we seek to determine which positions are more likely to be affected by the relative age effect. This study identifies three positions (Run- ning Backs (RBs), Tight Ends (TEs) and Defensive Linemen (DLs)) in which the percentage of players born in the first two birth-quarters out-number those in the 4The relative age effect and the birthplace effect in the National Football League - Cheung Po-tak (1995048736) latter two birth-quarters by the biggest margin. Therefore, it is suggested that these three positions are most heavily affected by the relative age effect. As these positions are characterised by having a very high demand for physical fit- ness and overall athleticism, it is argued that the relative age effect will only bene- fit the relatively older athletes in terms of their physical development. The ab- sence of the relative age effect in positions requiring higher intelligence and men- tal capacity, such as Quarterbacks (QBs), suggests that the relatively older athletes do not enjoy any advantage over the relatively younger ones in this aspect. A further analysis was also carried out within the thesis, concerning the first-round picks of the NFL draft since 1990s, through which we could see whether the birthdate distribution of these high draft picks is similar to that of the players on the 2004 NFL rosters. It has been found that the biggest difference exist among the QBs and TEs, where the relatively older QBs and TEs are more likely to be selected in the first round when compared with the relatively younger ones. To date, few studies have been carried out to analyse the birthplace ef- fect among athletes. It has been recently suggested by Cote, McDonald, Baker 5The relative age effect and the birthplace effect in the National Football League - Cheung Po-tak (1995048736) and Abernethy (2005) that athletes born in cities that are within a certain popula- tion range are more likely to succeed than those born in cities of other sizes, and athletes from the rural areas have a better chance to break into the professional leagues than the urban athletes do. The remainder of this thesis is a statistical analysis on the birthplace effect of the NFL players, to see if a critical population range exists, and to find out whether the odds of becoming an NFL player is re- lated to the populatio