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Activity Number: 342 - SPEED: Sports to Fire: Fascinating Applications of Statistics
Type: Contributed
Date/Time: Tuesday, July 31, 2018 : 10:30 AM to 12:20 PM
Sponsor: Section on Statistics in Sports
Abstract #330292 Presentation
Title: Assessing the Impact of Practice Restriction Rules on Injury Rates in the National Football League (NFL)
Author(s): Zachary Binney* and Cecile Janssens and Kyle E Hammond and Mitchel Klein and Michael Goodman
Companies: Rollins School of Public Health, Emory University and Rollins School of Public Health, Emory University and Emory University School of Medicine and Rollins School of Public Health, Emory University and Emory University
Keywords: sports; football; injuries; policy change; rule change

The National Football League's (NFL) 2011 collective bargaining agreement (CBA) placed limits on practices in an effort to reduce injuries. Some coaches are concerned it has had the opposite effect due to poorer conditioning. We sought to assess whether the CBA's practice restrictions affected the number of overall or conditioning-dependent injuries. We identified non-head, non-illness injuries causing at least one missed game from 2007-2016 using a database of NFL injury reports. We calculated overall and conditioning-dependent injury counts by season and compared the results pre- and post-CBA. We used Poisson interrupted time series models to account for a pre-CBA rise in injuries and assess whether a.) there was an immediate change post-CBA change or b.) if the pre-CBA trend accelerated post-CBA. The number of injuries rose steadily from 701 in 2007 to 804 (15%) in 2016. Conditioning-dependent injuries increased 38% from 197 in 2007 to 271 in 2011 before plateauing around 220-240 injuries from 2012-16. Our models did not identify any detrimental effects of the CBA on injury counts. However, other concurrent rule changes limit causal inferences about the practice restrictions.

Authors who are presenting talks have a * after their name.

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