Analysis of factors influencing on home advantage in professional baseball using odds ratio

• Published in: The Japan Journal of Coaching Studies Vol. 26; no. 1; pp. 73 - 82
• Main Author: Aoyagi, Osamu
• Format: Journal Article
• Language: English; Japanese
• Published: The Japan Journal of Coaching Studies 20.11.2012
• Subjects: Audience factor; Learning factor; Multiple regression analysis; Travel factor
• ISSN: 2185-1646; 2434-0510
• DOI: 10.24776/jcoaching.26.1_73

In sports that are played both home and away, it is thought that home field confers an advantage, referred to as “home (field) advantage” (HA). HA has traditionally been defined as a more than 50％ probability of winning home games. However, this advantage does not necessarily apply to an individual team or a specific combination of teams, as HA depends on the strength of the teams playing. This study used odds ratios to investigate whether HA exists and the relationship between HA and “learning,” “travel,” and “audience/crowd” factors on Japanese Professional Baseball, in which HA is assumed to occur frequently. Archival data of all games of Japanese Professional Baseball from 2005 to 2008 were used. In addition, a) travel distance and b) travel time were used as travel factors; c) interleague games was used as a learning factor; and d) audience size, e) audience density, f) presence or absence of a dome at the home stadium, and g) stadium capacity were used as audience/crowd factors. The learning factor was assessed by comparing odds ratios in intraleague games with those in interleague games. Correlational analysis between odds ratios and travel and audience factors was applied. Results were as follows: 1） Constant and definite HA was found in Japanese Professional Baseball as in soccer, ice hockey, and basketball, all of which use a home and away system. However, the degree of HA in baseball was no more remarkable than in other sports. 2） HA between teams did not occur randomly in all teams, but did occur in specific teams, such as the Chunichi Dragons in the Central League and the Rakuten Eagles in the Pacific League. 3） Although findings were not consistent among years, a partial effect of the learning factor was found when comparing HA in intraleague and interleague games. 4） Simple correlational analysis of HA and travel and audience factors showed no significant correlation. 5） Results of multiple correlational analysis using travel and audience factors as independent variables showed some significant multiple correlation coefficients. In particular, significant regression coefficients and partial correlation coefficients were shown regarding the audience factor. HA was present in the Japanese Professional Baseball League. Although the travel factor had little effect on HA, the learning and, in particular, audience/crowd factors significantly influenced HA. Methods that systematically increased the number of fans and organization of fan clubs were shown to contribute to HA. However, as this role is filled by a teamʼs front office staff, coaches should communicate with front office staff and encourage them to focus on these factors to help their team make the most of HA.