A comprehensive survey of the home advantage in American football (2401.16392v3)

Abstract: The existence and justification to the home advantage -- the benefit a sports team receives when playing at home -- has been studied across sport. The majority of research on this topic is limited to individual leagues in short time frames, which hinders extrapolation and a deeper understanding of possible causes. Using nearly two decades of data from the National Football League (NFL), the National Collegiate Athletic Association (NCAA), and high schools from across the United States, we provide a uniform approach to understanding the home advantage in American football. Our findings suggest home advantage is declining in the NFL and the highest levels of collegiate football, but not in amateur football. This increases the possibility that characteristics of the NCAA and NFL, such as travel improvements and instant replay, have helped level the playing field.

• The paper employs Bayesian analysis over nearly two decades to quantify home advantage trends in various football tiers.
• It contrasts three models (constant, linear, and time-varying) and finds modest declines in NFL HA and significant trends at the NCAA level.
• Findings suggest that improved officiating and travel logistics may reduce HA in professional and college football, while high school patterns vary.

A Comprehensive Survey of Home Advantage in American Football

The paper presents a detailed examination of the home advantage (HA) in American football across three significant tiers—National Football League (NFL), National Collegiate Athletic Association (NCAA), and high school football within the United States. Spanning nearly two decades of data, the authors aim to elucidate the temporal trends in home advantage and postulate potential contributing factors to any observed changes.

Methodology Overview

The authors employ Bayesian modeling, utilizing data from the NFL, NCAA, and high schools across all 50 states. Three separate Bayesian models are formulated to measure changes in HA: a constant HA model, a linear HA model, and a time-varying HA model. Bayesian modeling allows the authors to obtain comprehensive posterior distributions for the change in home advantage, providing a robust framework for statistical inference. Critical model comparison is performed using expected log pointwise predictive density (ELPD) to select the model with optimal predictive capabilities across various strata of football.

Key Findings

The analysis reveals heterogeneity in HA trends dependent on the level of play:

1. NFL: Model results indicate a modest decline in home advantage, although not to an exceptional degree. This aligns well with recent trends observing a diminishing HA in professional American sports.
2. NCAA: The paper finds the most significant decline at the FBS level, with clear temporal trends suggesting HA lessening over time. While FCS and Division II also exhibit HA declines, these trends are less pronounced.
3. High School Football: In contrast, high school football shows a varied pattern, with several states displaying increasing trends and others showing stagnation or slight decline over the paper period.

Implications

The results suggest several potential drivers for changes in home advantage. The introduction and evolution of instant replay in the NFL and NCAA potentially mitigate biases in officiating that historically favored home teams. Moreover, substantial improvements in travel logistics for NCAA teams, particularly at top-tier FBS schools, may alleviate some historical disadvantages faced by traveling teams.

Conversely, high school football remains largely unaffected by technological and logistical advancements affecting higher levels. Decisions about travel and game locations are grounded in logistical constraints rather than optimized sport-specific adjustments seen elsewhere.

Theoretical and Practical Implications

The declining HA in college and professional football could indicate that enhancements in fairness and equity, particularly with instant replay and improved travel logistics, are effectively leveling the competitive playing field. This paper highlights the importance of accounting for relative team strength, given that empirical estimations are often inflated due to stronger teams hosting more home games.

The potential persistence of HA in high school football necessitates further investigation. Differences may result from factors such as travel methods, crowd influence, and resource allocation, offering a fertile ground for future research.

Future Developments

Future research should consider integrating approaches that account for nonlinear trends in HA changes and further exploration of different sports to discern broader patterns. Also, investigation into other potential factors, such as psychological aspects or team composition changes, could provide additional insights into HA dynamics.

Overall, this paper contributes significantly to understanding the variance in HA across different levels of American football, offering insights relevant to league administrators, coaches, and those interested in sports analytics. Its findings highlight the importance of nuanced and context-specific considerations when analyzing performance benefits linked to playing at home.