Manuscript The Cauldron Has Cooled Down: A Systematic Literature Review on COVID-19, Ghost Games, and Home Advantage in Football from a Behavioral Science Perspective Michael Christian Leitner 1,2, Frank Daumann 3, Florian Follert 4 & Fabio Richlan 1,2 1 Centre for Cognitive Neuroscience (CCNS), University of Salzburg, Austria 2 Department of Psychology, University of Salzburg, Austria 3 Faculty of Social and Behavioural Sciences, Friedrich-Schiller-University Jena, Germany 4 Faculty of Management, Seeburg Castle University, Austria Draft version 1.1, 29/05/2021 This paper has not been peer reviewed yet. Please do not copy or cite without author’s permission. The authors declare that they have no conflict of interest. Corresponding author: Michael C. Leitner / University of Salzburg / Centre for Cognitive Neuroscience / Department of Psychology / Hellbrunnerstrasse 34 / 5020 Salzburg / Austria [email protected] Michael Christian Leitner, Frank Daumann, Florian Follert & Fabio Richlan The Cauldron Has Cooled Down: A Systematic Literature Review on COVID-19, Ghost Games, and Home Advantage in Football from a Behavioral Science Perspective Abstract Research question: The phenomenon of home advantage (or home bias) is well-analyzed in the scientific literature and is traditionally an interdisciplinary topic. So far, the phenomenon has been difficult to study because, although there have always been single matches where the spectators were excluded, this never happened globally to all teams within a league or even across leagues. Thus, several studies examined the influence of supporters by comparing matches before the COVID-19 restrictions with so-called ghost games during the pandemic. Research method: To synthesize the existing knowledge after over a year of ghost games and to offer the scientific community and other stakeholders an overview regarding the numerous studies, we provide a systematic literature review that summarizes the main findings of 16 empirical studies and discusses the results accordingly. Results: Our findings - based on 16 studies - indicate that ghost games have a considerable impact on the phenomenon of home advantage. No study found an increased home advantage in ghost games. Rather, our results show that 13 (from 16 included) analyzed studies conclude – based on their individually examined data – a more or less significant decrease of home advantage in ghost games. Implications: We conclude that our findings are highly relevant from a both socio-economic and behavioral perspective and highlight the indirect and direct influence of spectators and fans on football. Our results have – besides for the scientific community – a high importance for sports and team managers, media executives, fan representatives and other persons responsible. Keywords: fans, home advantage, football, systematic literature review, COVID-19 2 Michael Christian Leitner, Frank Daumann, Florian Follert & Fabio Richlan The Cauldron Has Cooled Down: A Systematic Literature Review on COVID-19, Ghost Games, and Home Advantage in Football from a Behavioral Science Perspective Introduction Fans love football and especially the excitement and uncertainty of the game (Schreyer et al., 2018). They are also commonly referred to as the “12th man” (Saunders, 2020) and constitute an important part of the modern entertainment product “professional football” (Edensor, 2015). For the players, too, it obviously has a meaning whether they play in their home venue in front of their home crowd, on “their own corner” in the first or second half of a match, or on which goal the decisive penalty shootout in a play-off or cup competition takes place. From a scientific perspective, fans are seen as an (external) determinant in the production of sporting success and, consequently, of economic success (Dietl et al., 2005; Daumann, 2019). It can hardly be denied that football benefits greatly from active spectators (Rudolph et al., 2017), whether through ticket revenues or through the typical stadium atmosphere that gives the product its special marketability (Woratschek et al., 2019). These benefits are also accompanied by (external) costs – such as violence (Di Domizio & Caruso, 2015; Dunning et al., 1986; Mause 2020) – posing considerable challenges for sporting and political players that regularly have to be borne by the clubs and the general public. In the present review, we concentrate on the positive contribution of football fans and suggest interpreting fans as important production factors (Follert et al., 2020). In this context, the influence of fans on the game results mainly from the home advantage (Courney & Carron, 1992) (or home bias) which is well-documented in professional football and even reflected in the regulations of international competitions like UEFA Champions League1. The home advantage states that home teams win more than half of the games (excluding draws) when home and away games are evenly distributed in a season (Courney & Carron, 1992). Thus, a corresponding relative advantage of home teams over away teams can be assumed – albeit to varying degrees and based on different explanations (Buraimo et al., 2012; Courneya & Carron, 1992; Pollard, 2008; Ponzo & Scoppa, 2018; Schwartz & Barsky, 1977). One factor that can be analyzed in the current COVID-19 situation, leading to almost laboratory-like conditions in stadiums, is the influence of (missing) fans on various social and sporting aspects during a football match (Bryson et al., 2020). In particular, the influences of the audience on the behavior and decisions of the referees (Dohmen & Sauermann, 2016) and 1 In case of a tie on points after two matches, a goal scored away from home counts double. 3 Michael Christian Leitner, Frank Daumann, Florian Follert & Fabio Richlan The Cauldron Has Cooled Down: A Systematic Literature Review on COVID-19, Ghost Games, and Home Advantage in Football from a Behavioral Science Perspective on the behavior and motivation of the players (Ponzo & Scoppa, 2018) can be specifically investigated. After screening the broad relevant empirical literature as an outcome of the ghost games during the COVID-19 lockdowns, the additional benefit of another empirical study seems limited. For the international scientific community, it may be more important to bundle and synthesize the findings from this field. To this end, we provide a comprehensive overview of the empirical studies conducted so far during the match breakdown, the so-called “ghost games” period in the COVID-19 pandemic. These studies show that fans have to be considered as a significant production factor that can even influence the sporting outcome of a match. We aim to provide a comprehensive overview concerning the variety of empirical studies and to analyze their results from the view of behavioral economics. The paper follows the following structure: In section 2, we provide a theoretical background for our literature review where we highlight the crucial findings concerning home advantages in sports as well as the important role of spectators for the production of a typical stadium atmosphere particularly in professional football. In section 3 we present the results of a systematic literature review that offers an overview on the relevant empirical studies to the scientific community and other stakeholders in the sports industry. Based on our findings we discuss the main results and the limitations of our study. In section 4 we present several implications for further research and sports business before we highlight some conclusions in section 5. Theoretical background Home advantage in professional sports. Following the seminal work by Courneya and Carron (1992) we understand a home advantage as “the consistent finding that home teams in sport competitions win over 50% of the games played under a balanced home and away schedule” (p. 13). First empirical evidence for the home advantage in sport competition was provided by Schwartz and Barsky (1977) who analyzed the major leagues in baseball, football, hockey, and basketball as well as the U.S. college competition in football and basketball. In the literature on sport psychology and sport economics, the home advantage effect is attributed to various influencing parameters, which Courneya and Carron (1992) systematize as follows: ● Game location factors (crowd, learning, travel, rules) ● Critical psychological states (competitors, coaches, officials) 4 Michael Christian Leitner, Frank Daumann, Florian Follert & Fabio Richlan The Cauldron Has Cooled Down: A Systematic Literature Review on COVID-19, Ghost Games, and Home Advantage in Football from a Behavioral Science Perspective ● Critical behavioral states (competitors, coaches, officials) ● Performance outcomes (primary, secondary, tertiary) The game location factors comprise four determinants that can affect the visiting and home teams differently. This includes the crowd factor (1.), according to which the home team receives greater support at home than the visiting team. Under learning/familiarity factors (2.) it is assumed that the home team is better acquainted with the location and also has the possibility to redesign it at short notice. In football, the watering of the lawn is likely to be relevant here as an example. Under the heading travel factors (3.) hides the fact that the visiting team has to travel to the venue and thus has to take on inconveniences to which the home team is not exposed. Finally, under rule factors (4.), components of the set of rules