Abstract We test for the existence of relative age effects in professional American football. In a sample of 18,898 football players born on or after 1940, there is an excess of January and February births – consistent with a relative age effect associated with calendar year – as well as a slight increase in September births – consistent with the fact that some football players we analyze attended high school in states with fall school cutoff dates. We consider the possibility that relative age effects may affect skilled football positions more than positions relying heavily on player weight, and we find suggestive evidence of this. Lastly, and contrary to what has recently been shown in professional hockey, we find no evidence that misguided preferences for relatively older players lead to selection-based inefficiencies in football player drafting. Our results have implications for evaluating potential football players and speak broadly to the role of physiological factors beyond player control on athletic success.

中文翻译：

---

美式职业足球的相对年龄效应

摘要我们测试了职业橄榄球中相对年龄效应的存在。在1940年或之后出生的18,898名足球运动员样本中，一月和二月的出生人数过多-与日历年相关的相对年龄效应相符-九月的出生人数略有增加-与事实相吻合我们分析的足球运动员在各州的秋季入学截止日期为高中。我们认为相对年龄的影响可能比熟练地依赖球员体重的位置对技术性足球位置的影响更大，并且我们发现了暗示性的证据。最后，与最近在职业曲棍球比赛中出现的情况相反，我们没有证据表明，相对年长的球员的误导偏好会导致选拔球员效率低下。我们的结果对评估潜在的足球运动员具有启示意义，并广泛地讨论了生理因素在运动员取得运动成功后所无法控制的作用。