Home advantage

There are many causes that attribute to home advantage, such as crowd involvement, travel considerations, and environmental factors. The most commonly cited factors of home advantage are usually factors which are difficult to measure and so even their existence is debated. Most of these are psychological in nature: the home teams are familiar with the playing venue; they can lodge in their homes, rather than in a hotel, and so have less far to travel before the game; and they have the psychological support of the home fans.

Other factors, however, are easier to detect and can have noticeable effects on the outcome of the game. In American football, for instance, the crowd often makes as much noise as it can when the visiting team is about to run a play. That can make it very difficult for the visiting team's quarterback to call audible play changes, or for any player to hear the snap count. In contrast, the crowd is often quiet while the home team is on offense, and that enables the quarterback to use the hard count intended to draw the defense offsides as the defense can hear the hard count. In basketball, when a visiting player is making a free throw, home fans behind the backboard typically wave their arms or other objects in an attempt to break the visiting player's focus on making the shot. Environmental factors such as weather and altitude are easy to measure, yet their effects are debatable, as both teams have to play in the same conditions; but the home team may be more acclimated to local conditions with difficult environments, such as extremely warm or cold weather, or high altitude (such as the case of Denver teams, as well as the Mexico national football team, many of whose home matches are played in Mexico City).

The stadium or arena will typically be filled with home supporters, who are sometimes described as being as valuable as an extra player for the home team. The home fans can sometimes create a psychological lift by cheering loudly for their team when good things happen in the game. The home crowd can also intimidate visiting players by booing, whistling, or heckling. Generally the home fans vastly outnumber the visiting team's supporters. While some visiting fans may travel to attend the game, home team fans will generally have better access to tickets and easier transport to the event, thus in most cases they outnumber the visitors' fans (although in local derbies and crosstown rivalries this may not always be the case). In some sports, such as association football, sections of the stadium will be reserved for supporters of one team or the other (to prevent fan violence) but the home team's fans will have the bulk of the seating available to them. In addition, stadium/arena light shows, sound effects, fireworks, cheerleaders, and other means to enliven the crowd will be in support of the home team. Stadium announcers in many sports will emphasize the home team's goals and lineup to excite the crowd.

Ryan Boyko, a research assistant in the Department of Psychology in the Faculty of Arts and Sciences at Harvard University, studied 5,000 English Premier League games from 1992 to 2006, to discern any officiating bias and the influence of home crowds. The data was published in the Journal of Sports Sciences and suggested that for every additional 10,000 people attending, home team advantage increased by 0.1 goals. Additionally, his study proved what many football fans already suspect: that home teams are likely to be awarded more penalty kicks, but crucially, this is more likely with inexperienced referees. So, consideration of referee profiles should clearly be a refinement for home field advantage statistics.[4]

Further, home players can be accustomed to peculiar environmental conditions of their home area. The city of Denver, being a mile (1609 m) above sea level, has thinner air, enough so that it affects the stamina of athletes whose bodies are not used to it. Although baseball is less aerobically demanding than many other sports, high altitude affects that sport's game play in several important ways. Denver's combination of altitude and a semi-arid climate (the city averages only about 16 in/400 mm precipitation annually) allows fly balls to travel about 10% farther than at sea level, and also slightly reduces the ability of a pitcher to throw an effective breaking ball. The low humidity also causes baseballs to dry out, making it harder for pitchers to grip them and further reducing their ability to throw breaking balls. Consequently, the Colorado Rockies have a very large home advantage, with a 30% better home than away record. This anomaly has been countered with Colorado's innovative use of humidors to keep the baseballs from drying out. Denver's altitude advantage has also come into play in gridiron football; the longest field goal in National Football League history took place in Denver, as did the longest recorded punt. The national association football team of Bolivia also enjoys the advantage of playing at high altitude: at home during World Cup qualifiers at the even more extreme 3,600 m (11,800 ft) altitude of La Paz they have even been known to beat Brazil, a team regularly ranked number one in the FIFA World Rankings. More recently, Bolivia beat Argentina, who were ranked sixth in the world, 6–1 on April 1, 2009, Argentina's heaviest defeat since 1958.[5] In cricket, the condition of the pitch and the behaviour of the ball when it bounces off the pitch varies significantly in different parts of the world, and consequently the players on the visiting team must adjust to the ball behaving in an unfamiliar way to be successful on foreign surfaces; additionally, the home team has the right to adjust the preparation of its pitches in a manner which specifically enhances its own strengths or exacerbates its opponent's weaknesses.[6]

The weather can also play a major factor. For example, the February average temperature minimum in Tel Aviv, Israel is 50 °F (10 °C), while the average at the same time in Kazan, Russia is 10 °F (−12 °C), with snow being common. This means that when Rubin Kazan played at home to Hapoel Tel Aviv in the 2009-10 UEFA Europa League, Hapoel needed to acclimatize and were therefore at a disadvantage. Hapoel duly lost the match 3-0. This advantage, however, can also be a disadvantage to the home team, as weather conditions can impede the home team as much as the visitors: the Buffalo Bills, whose home stadium (Bills Stadium) is subject to high and unpredictable winds and lake-effect snow in the late fall and early winter, regularly suffer large numbers of injuries late in the season.

Sometimes the unique attributes of a stadium create a home-field advantage. The unique off-white Teflon-coated roof of the Hubert H. Humphrey Metrodome trapped and reflected noise to such an extent that it was distracting or even harmful. This, combined with the color of the roof, caused opposing baseball players to commit more errors in the Dome than in other ballparks. While this is no longer an issue for opponents of the Minnesota Twins with that team's 2010 move to the open-air Target Field, it remained important to the many college baseball teams that played games in the Dome until its late 2013 closing. The parquet floor at the Boston Celtics' former home of Boston Garden contained many defects, which were said to give the Celtics, who were more likely to be familiar with the playing surface, an advantage. During the 1985–1986 season, the Larry Bird-led Celtics posted a home court record of 40–1; this record still stands in the NBA. Memorial Gymnasium, the venue for men's and women's basketball at Vanderbilt University, was built in 1952 with the team benches at the ends of the court instead of along one of the sidelines, a setup that was not unusual at the time. However, the configuration is now unique in U.S. major-college sports, and has been said to give the Commodores an edge because opposing coaches are not used to directing their teams from the baseline. Cherry Hill Arena, a New Jersey-based arena in the southern suburbs of Philadelphia, had a number of idiosyncrasies that its home teams used to their advantage but earned the arena an extremely poor reputation, including a slanted ice surface that forced opponents to skate the majority of the game uphill and lack of showers for the visiting team.

Sports Illustrated, in a 17 January 2011 article, reported that home crowds, rigor of travel for visiting teams, scheduling, and unique home field characteristics, were not factors in giving home teams an advantage. The journal concluded that it was favorable treatment by game officials and referees that conferred advantages on home teams. They stated that sports officials are unwittingly and psychologically influenced by home crowds and the influence is significant enough to affect the outcomes of sporting events in favor of the home team.[7]

Other research has found that crowd support, travel fatigue, geographical distance, pitch familiarity, and referee bias do not have a strong effect when each factor is considered alone suggesting that it is the combination of several different factors that creates the overall home advantage effect. An evolutionary psychology explanation for the home advantage effect refers to observed behavioral and physiological responses in animals when they are defending their home territory against intruders. This causes a rise in aggression and testosterone levels in the defenders. A similar effect has been observed in football with testosterone levels being significantly higher in home games than in away games. Goalkeepers, the last line of defense, have particularly strong testosterone changes when playing against a bitter rival as compared to a training season. How testosterone may influence results is unclear but may include cognitive effects such as motivation and physiological effects such as reaction time.[3]

An extreme example of home advantage was the 2013 Nigeria Premier League; each of the 20 teams lost at most 3 of 19 home matches and won at most 3 of 19 away matches. Paul Doyle ascribed this to visiting teams' facing "violent crowds, questionable refereeing and [...] [a]rriving just before kick-off after long road trips, often on hazardous surfaces".[8]

In ice hockey, there are at least three distinct rule-related advantages for the home team. The first is referred to as "last change", where during stoppages of play, the home team is allowed to make player substitutions after the visiting team does. This allows the home team to obtain favorable player matchups. This rule makes the home team designation important even in games played on neutral ice. Traditionally, the second advantage was that when lining up for the face-off, the away team's centre always had to place his stick on the ice before the centre of the home team. However, in both the NHL and international rule sets, this now applies only for face-offs at the centre-ice spot; when a face-off takes place anywhere else on the ice, the defending centre has to place his stick first. The centre who is allowed to place his stick last gains the ability to time the face-off better and gives him greater odds of winning it. The third advantage is that the home team has the benefit of choosing whether to take the first or second attempt in a shootout.

In baseball, the home team – which bats in the bottom half of each inning – enjoys the advantage of being able to end the game immediately if it has the lead in the ninth inning (or other scheduled final inning) or in extra innings. If the home team is leading at the end of the top half of the ninth inning, the game ends without the bottom half being played. If the home team is trailing or the score is tied in the bottom half of the ninth inning or any extra inning, the game ends immediately if the home team takes the lead; the visiting team does not get another opportunity to score and the home team does not have to protect their lead. On the other hand, if the visiting team has the lead when the top half of the ninth inning or extra inning ends, the home team still gets an opportunity to score and so the visiting team must protect their lead.

Additionally in baseball, the host team is familiar with the unique dimensions of their home field yielding them advantages (pitching, hitting, fielding) over visiting teams. In addition, in Major League Baseball, the home league's rules concerning the designated hitter (DH) are followed during interleague games, including the World Series. This puts AL teams at a disadvantage when they play in NL parks, as AL pitchers are typically not used to batting nor baserunning. NL teams at AL parks are at a disadvantage because a player who does not play often will have to bat an entire game, usually on consecutive nights. The NL team's DH is a pinch-hitter who bats perhaps once every two or three games during the season, or alternates in a platoon system with other players (such as a catcher who does not start because the starting pitcher uses the other catcher), while the AL team's DH bats three or more times a game throughout the season.[9]

For games at home, the hosting team will have the advantage of playing with their first choice uniform/kit, rather than their alternate colors. A team's identity is often partly or mostly based on its home colors (for example, the All Blacks of New Zealand). In the NFL and most NCAA football conferences, the home team has the choice to wear colored or white jerseys. Many teams from warm-weather cities, will wear their white jerseys at home, at least early in the season, forcing their opponent to wear dark jerseys in the hot weather.

A rule in American high school football (except Texas, which plays by NCAA rules) requiring the home team to wear dark jerseys and the visiting team to wear white jerseys may work as a disadvantage to the home team in hot-weather games.

Comparison of home advantage in European top-level football leagues between the 2007/2008 and 2016/2017 seasons. Method is based on Jeffrey Divergence and the procedure is described in detail in Marek and Vávra (2020).[10] The final components of graph show leagues with similar home advantages.

Measuring the home-field advantage of a team (in a league with balanced schedule) requires a determination of the number of opponents for which the result at home-field was better (${\displaystyle k_{1}}$), same (${\displaystyle k_{0}}$), and worse (${\displaystyle k_{-1}}$). Goals scored and conceded – in so called combined measure of home team advantage – are used to determine which results are better, same, and which are worse. Given two results between teams ${\displaystyle T_{1}}$ and ${\displaystyle T_{2}}$, ${\displaystyle h_{T_{1}}:a_{T_{2}}}$ played at ${\displaystyle T_{1}}$'s field and ${\displaystyle h_{T_{2}}:a_{T_{1}}}$played at ${\displaystyle T_{2}}$'s field, we can compute differences in scores (e.g. from ${\displaystyle T_{1}}$'s point of view): ${\displaystyle d_{h,T_{1}}=h_{T_{1}}-a_{T_{2}}}$and ${\displaystyle d_{a,T_{1}}=a_{T_{1}}-h_{T_{2}}}$. Team ${\displaystyle T_{1}}$ played better at home field if ${\displaystyle d_{h,T_{1}}>d_{a,T_{1}}}$, and ${\displaystyle T_{1}}$ played better at away field if ${\displaystyle d_{h,T_{1}}<d_{a,T_{1}}}$ (for example, if Arsenal won 3–1 at home against Chelsea, i.e. ${\displaystyle d_{h,Arsenal}=2}$, and Arsenal won 3–0 at Chelsea, i.e. ${\displaystyle d_{a,Arsenal}=3}$, then the result for Arsenal at home was worse). Same approach has to be used for all opponents in one season to obtain ${\displaystyle k_{1}}$, ${\displaystyle k_{0}}$, and ${\displaystyle k_{-1}}$.

Values of ${\displaystyle k_{1}}$, ${\displaystyle k_{0}}$, and ${\displaystyle k_{-1}}$ are used to estimate probabilities as ${\displaystyle {\hat {p}}_{r}={\frac {k_{r}+1}{K+3}},r=-1,0,1}$, where ${\displaystyle K}$ is total number of opponents in a league (this is Bayesian estimator). To test hypothesis that home-field advantage is statistically significant we can compute ${\displaystyle P(p_{1}>p_{-1})=1-I_{1/2}(k_{1}+1,k_{-1}+1)}$, where ${\displaystyle I_{1/2}()}$ is incomplete gamma function. For example, Newcastle in 2015/2016 English Premier League season recorded better result at home field for 13 opponents, same result with 4 opponents, and worse result for two opponents; therefore ${\displaystyle P(p_{1}>p_{-1})=1-I_{1/2}(14,3)=0.998}$ and hypothesis about home team advantage can be accepted. This procedure was introduced and applied by Marek and Vávra (2017)[11] on English Premier League seasons 1992/1993 – 2015/2016.

Marek and Vávra (2018)[12] described procedure which allows to use observed counts of combined measure of home team advantage (${\displaystyle k_{1}}$, ${\displaystyle k_{0}}$, and ${\displaystyle k_{-1}}$) in two leagues to be compared by the test for homogeneity of parallel samples (for the test see Rao (2002)[13]). The second proposed approach is based on distance between estimated probability description of home team advantage in two leagues ( ${\displaystyle {\hat {p}}_{r}={\frac {k_{r}}{K}},r=-1,0,1}$) which can be measured by Jeffrey divergence (a symmetric version of Kullback–Leibler divergence). They tested five top level English football leagues and two top level Spanish leagues between 2007/2008 and 2016/2017 season. The main result is that home team advantage in Spain is stronger. Spanish La Liga has the strongest home team advantage, and English football league two has the lowest home team advantage, among analysed leagues.

Comparison of home advantage in 19 European football leagues between the 2007/2008 and 2016/2017 seasons was made in Marek and Vávra (2020).[10] They found that, among the analysed leagues, the Super League Greece had the strongest home advantage and English Football League Two had the lowest home advantage.

In the 2018 Major League Baseball regular season, the home team won 1,277 games (52.6%), and the away team won 1,149 games (47.4%). These totals do not include the six games played at neutral sites (though all of the neutral-site games had a designated "home" team).

• The team with the best overall record, the Boston Red Sox, finished 108–54, going 57–24 at home and 51–30 away. Of their wins, 52.8% were at home, and 55.6% of their losses were on the road.
• The team with the worst record, the Baltimore Orioles, went 47–115 (28–53 at home, 19–62 away). Of their total wins, 59.6% were at home, and 53.9% of their losses were away.
• The largest differential between home and road records was that of the Philadelphia Phillies, going 48–32 at home, 31–50 away, and winning their only neutral-site game as the designated home team. Exactly 60% of their wins were in their home park, and 61.0% of their losses were on the road.
• An especially anomalous home/away split was that of the Houston Astros, whose 103–59 record was second-best in MLB. They were 11 games better on the road than at home (46–35 home, 57–24 away). Of their wins, 44.6% were at home, while 40.7% of their losses were away.
• The 2019 World Series is the first 7-game series in the history of major North American sports where all seven games were won by the road team.[18] Ironically, both finalists, the Washington Nationals and the Houston Astros, had been stronger at home than on the road in both the regular season and playoffs, until the World Series.[19]

In the 2018–19 NBA regular season, the home team won 1,230 games (71%), and the away team won 501 games (29%).

• The team with the best overall record, the Milwaukee Bucks, finished 60–22, going 33–8 at home and 27–14 away. In all, 55% of their wins were at home, and 64% of their losses were on the road.
• The Denver Nuggets had the best home record, going 34–7 at home, but went 20–21 away. This meant that 63% of their wins were at home, and 75% of their losses were away.
• The only teams with a better record on the road than at home were the Chicago Bulls and the Miami Heat, going 9–32 and 19–22 at home and 13–28 and 20–21 on the road, respectively.

Across the 2008, 2010, and 2011 seasons of the Indian Premier League, the home team won 95 games (54.3%), and the away team won 80 games (45.7%).[20]

At least some degree of home field advantage has been recorded in almost every National Football League season; each year, designated home teams have won more games than lost. The 2020 NFL season, played in empty and near-empty stadiums, was the first in which no advantage was recorded: home teams that year finished 127–128–1 (.498).[21]

In the 2019 Stanley Cup Playoffs, for the first time in NHL history all division winners (who had home-ice advantage) were eliminated in the first round as all the wild-cards advanced to the second round.[22] The Columbus Blue Jackets won a playoff series for the first time, defeating the first-place Lightning in four games, and marking the first time in Stanley Cup playoff history that the Presidents' Trophy winners were swept in the opening round, and the first time since 2012 that the Presidents' Trophy winners were defeated in the opening round. They were soon followed by the Calgary Flames, who with their five-game loss to the Colorado Avalanche, ensured that for the first time in NHL history,[23] neither of the conference number one seeds advanced to the second round. After that, the two remaining division winners, the Nashville Predators and Washington Capitals, were each eliminated in an overtime game, the Predators in six by the Dallas Stars, and the Capitals in seven by the Carolina Hurricanes.

In the 2018–19 Premier League, the home team won 181 matches (47%), the away team won 128 matches (34%), and teams drew in 71 matches (19%); however, this is considered an aberration, as home advantage has statistically been steadily declining for over a century. [24]

• Liverpool had 30 wins, 7 draws and 1 loss. They had 57% of their wins at home, and 100% of their losses away.
• Crystal Palace had 14 wins, 7 draws and 17 losses. They had 64% of their wins away, and 53% of their losses at home.