Home advantage

In team sports, the term home advantage – also called home ground, home field, home-field advantage, home court, home-court advantage, defender's advantage or home-ice advantage – describes the benefit that the home team is said to gain over the visiting team. This benefit has been attributed to psychological effects supporting fans have on the competitors or referees; to psychological or physiological advantages of playing near home in familiar situations; to the disadvantages away teams suffer from changing time zones or climates, or from the rigors of travel; and, in some sports, to specific rules that favor the home team directly or indirectly. In baseball, in particular, the difference may also be the result of the home team having been assembled to take advantage of the idiosyncrasies of the home ballpark, such as the distances to the outfield walls; most other sports are played in standardized venues.

The term is also widely used in "best-of" playoff formats (e.g., best-of-seven) as being given to the team that is scheduled to play one more game at home than their opponent if all necessary games are played.

In many sports, such designations may also apply to games played at a neutral site; as the rules of various sports make different provisions for home and visiting teams. In baseball, for instance, the team designated the home team bats second in each inning, whereas the "visiting" team bats first.

Advantages
In most team sports, the home or hosting team is considered to have a significant advantage over the visitors. Due to this, many important games (such as playoff or elimination matches) in many sports have special rules for determining what match is played where. In association football, matches with two legs, one game played in each team's "home", are common. It is also common to hold important games at a neutral site, such as the Super Bowl, in which the location is determined years in advance. In many team sports in North America (including baseball, basketball, and ice hockey), playoff series are often held with a nearly equal number of games at each team's site. However, as it is usually beneficial to have an odd number of matches in a series (to prevent ties), the final home game is often awarded to the team that had the most success over the regular season.

An example is UEFA Champions League and UEFA Europa League home and away legs, with weaker teams often beating the favourites when playing at home. The World Cup victories of Uruguay (1930), Italy (1934), England (1966), Germany (1974), Argentina (1978) and France (1998) are all in part attributed to the fact that the World Cup was held in the winner's country. A 2006 study by The Times found that in the English Premiership, a home team can be expected to score 37.29% more goals than the away team, though this changes depending on the quality of the teams involved. Others have suggested that the increase in British medals during the 2012 Olympics may have been impacted by home court advantage. (However, having home court did not help Canada at the 1976 Montreal Olympics, the only Summer Games at which the hosting country failed to win a single gold medal.)

The strength of the home advantage varies for different sports, regions, seasons, and divisions. For all sports, it seems to be strongest in the early period after the creation of a new league. The effect seems to have become somewhat weaker in some sports in recent decades.

Adams & Kupper (1994) described home-field advantage as an expertise deficiency. They demonstrated that, in theory and in practice, home-field advantage decreases as superiority of performance increases. They also showed that home-field advantage is not applicable for no-hit major league baseball games for pitchers who either replicated performance by winning two or more no-hitters or amassed a large number of career wins. Their general finding was that home-field advantage is a metric for the inability to maintain performance independent of environment and that this metric is inversely related to variables of expertise.

In recognition of the difficulty in winning away matches, cup competitions in association football often invoke the away goals rule. Away goals can also sometimes be used to separate teams level on points and goal difference in league competitions.

Factors related to the location and the venue
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.

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. 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 exacerbates its own strengths or its opponent's weaknesses.

The weather can also play a major factor. For example, the February average temperature minimum in Tel Aviv, Israel is 50 F, while the average at the same time in Kazan, Russia is 10 F, 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 (New Era Field) 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 Vandy 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.

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.

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".

Factors related to the game rules
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 gets to bat last in each inning. If the game goes into extra innings, this can yield very real advantages when deciding strategies regarding base-stealing and sacrifice hits. 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 having to bat. 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.

In baseball, there is always a psychological home advantage when the game is tied or close in the 9th or in extra innings. The visiting team, if they are leading after batting in their half of the inning (the top), must face and record three outs against the home team in order to finish off and win the game. But the home team, upon scoring the go-ahead run in the bottom of the 9th or an extra inning, wins in sudden death without having to take the field defensively following their period at bat. If the home team is in the lead following the top of the 9th, the game ends at this point, and the bottom of the 9th is not played at all. There is no clear-cut, physical advantage because both teams are given the same number of opportunities (i.e. innings). The advantage is knowing how well one must perform in the last inning, if at all.

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 Major League Baseball, by tradition a team's home uniform has the team name on it (i.e. "Twins", "Mets", "Braves") and is typically white in color, while its away uniform has the name of its home city, state or region on it ("Minnesota", "New York", "Atlanta") and is grey or is the "dark" jersey (features the team's colors), although there are exceptions.

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.

Measuring and comparing of home-field advantage
Measuring the home-field advantage of a team (in a league with balanced schedule) requires to determine number of opponents for which the result at home-field was better ($$k_1$$), same ($$k_0$$), and worse ($$k_{-1}$$). 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 $$T_1$$ and $$T_2$$, $$h_{T_1}:a_{T_2}$$ played at $$T_1$$'s field and $$h_{T_2}:a_{T_1}$$played at $$T_2$$'s field, we can compute differences in scores (e.g. from $$T_1$$'s point of view): $$d_{h,T_1}=h_{T_1}-a_{T_2}$$and $$d_{a,T_1}=a_{T_1}-h_{T_2}$$. Team $$T_1$$ played better at home field if $$d_{h,T_1}>d_{a,T_1}$$, and $$T_1$$ played better at away field if $$d_{h,T_1}<d_{a,T_1}$$ (for example, if Arsenal won 3–1 at home against Chelsea, i.e. $$d_{h,Arsenal}=2$$, and Arsenal won 3–0 at Chelsea, i.e. $$d_{a,Arsenal}=3$$, then the result for Arsenal at home was worse). Same approach has to be used for all opponents in one season to obtain $$k_1$$, $$k_0$$, and $$k_{-1}$$.

Values of $$k_1$$, $$k_0$$, and $$k_{-1}$$ are used to estimate probabilities as $$\hat{p}_r=\frac{k_r+1}{K+3}, r=-1,0,1$$, where $$K$$ 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 $$P(p_1>p_{-1})=1-I_{1/2}(k_1+1,k_{-1}+1)$$, where $$I_{1/2}$$ 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 $$P(p_1>p_{-1})=1-I_{1/2}(14,3)=0.998$$ and hypothesis about home team advantage can be accepted. This procedure was introduced and applied by Marek and Vávra (2017) on English Premier League seasons 1992/1993 – 2015/2016.

Marek and Vávra (2018) described procedure which allows to use observed counts of combined measure of home team advantage ($$k_1$$, $$k_0$$, and $$k_{-1}$$) in two leagues to be compared by the test for homogeneity of parallel samples (for the test see Rao (2002) ). The second proposed approach is based on distance between estimated probability description of home team advantage in two leagues ( $$\hat{p}_r=\frac{k_r}{K}, r=-1,0,1$$) 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.

Gaining or losing home-field advantage
During the regular season for a sport, in the interest of fairness, schedulers try to ensure that each team plays an equal number of home and away games. Thus, having home-field advantage for any particular regular-season game is largely due to random chance. (This is only true for fully organized leagues with structured schedules; for a counterexample, college football schedules often have an imbalance in which the most successful and largest teams can negotiate more home appearances than mid-majors, a situation that was also prevalent in the early, disorganized years of the National Football League).

However, in the playoffs, home advantage is usually given to the team with the higher seed (which may or may not have the better record), as is case in the NFL, MLB, and NHL playoffs. One exception to this was MLB's World Series, which between 2003 and 2016, awarded home-field advantage to the team representing the league which won the All-Star Game that year, to help raise interest in the All-Star Game after a tie in 2002 (before 2003, home-field advantage alternated each year between the National League and the American League). The NBA is the only league that has home-court advantage based solely on which team has the best record (using various tiebreakers to settle the question should the teams finish with identical records).

Rugby union's European Rugby Champions Cup also uses a seeding system to determine home advantage in the quarterfinals (though not in the semifinals, where the nominal "home" teams are determined by a blind draw).

In many sports, playoffs consist of a 'series' of games played between two teams. These series are usually a best-of-5 or best-of-7 format, where the first team to win 3 or 4 games, respectively, wins the playoff. Since these best-of series always involve an odd number of games, it is impossible to guarantee that an equal number of games will be played at each team's home venue. As a result, one team must be scheduled to have one more home game than the other. This team is said to have home-field advantage for that playoff series.

During the course of these playoff series, however, sports announcers or columnists will sometimes mention a team "gaining" or "losing" home-field advantage. This can happen after a visiting team has just won a game in the series. In playoff series format, the home-field advantage is said to exist for whichever team would win the series if all remaining games in the series are won by the home team for that game. Therefore, it is possible for a visiting team to win a game and, hence, gain home-field advantage. This is somewhat similar to the concept of losing serve in tennis.

As an example, suppose that the San Francisco Giants and the Los Angeles Dodgers are about to play a best-of-seven series against each other. Four games will be played in San Francisco, while three will be played in Los Angeles. If the home team were to win each game, then the Giants would win four games, the Dodgers would win three games, and the Giants would win the series, so we say that San Francisco has the home-field advantage. However, suppose that the first game is played at the Giants' park and the visiting Dodgers win. Los Angeles now has one win, and there are three games remaining at each park. If the home team wins each of the remaining games, then the Dodgers will have won four games, while San Francisco will have won two (the last game at San Francisco would be omitted, as even if the Giants won, they'd still lose 4 games to 3). Since the Los Angeles Dodgers would win the series in such a scenario, it is said that they have taken home-field advantage away from the San Francisco Giants.

In some cup competitions, (for example the FA Cup in all rounds prior to the semi-final), home advantage is determined by a random drawing. However, if the initial match is drawn (tied), home advantage for the replay is given to the other team.

Neutral venues
For certain sporting events, home advantage may be removed by use of a neutral venue. This may be a national stadium that is not a home stadium to any club (for example Wembley Stadium hosts the FA Cup Final and semi-finals). Alternatively the neutral venue may be the home stadium of another club, such as was used historically to stage FA Cup semi-finals.

If the venue is chosen before the start of the competition however, it is still possible for one team to gain home field advantage. For example, in the European Cup/UEFA Champions League, there have been four instances where a club has managed to reach the final hosted in its own stadium (1957, 1965, 1984, and 2012). Most recently Bayern Munich played (and lost) the 2012 final at their home stadium of Allianz Arena, as it was chosen as the venue in January 2010. In the Champions League Final, however, if the "home" shirt colors of both teams conflict (e.g. both are red) then there is a draw which assigns one of the teams their "away" shirt. Not unlike the UEFA Champions League, the NFL's Super Bowl is played in a venue chosen years in advance of the game. It is possible for a team to reach the Super Bowl when it is played in their home stadium; this has never happened in the history of the game, though two games (XIV in 1980 and XIX in 1985) were played in neutral stadiums in the market area of one of the participating teams. Tickets are allocated equally between both competing teams in the Final, even if one side happens to be the home team.

Neutral-venue matches may arise out of necessity. For example, on December 12, 2010, the roof of the Minnesota Vikings' stadium, the Hubert H. Humphrey Metrodome collapsed due to a snowstorm. The Vikings were supposed to play against the New York Giants at the stadium the next day. The game was moved to the Detroit Lions' stadium, Ford Field. The following week, the Vikings' Monday Night Football game against the Chicago Bears was moved to the University of Minnesota's TCF Bank Stadium.

For the 1992–93 and 1993–94 seasons, the National Hockey League scheduled neutral site games. Each team played 41 home games, 41 road games, and 2 games at neutral sites (for a total of 84 games). Each club played one neutral site game as the designated home team and one as the designated road team. The neutral site games were eliminated starting with the 1995–96 season, which reduced the regular season to 82 games per team.

A requirement to play home matches at a neutral venue has been used as a punishment by UEFA for teams whose fans cause disturbances at a previous match. For example, after the violent clashes after the Turkey-Switzerland game in 2005, UEFA punished the Turkish team with playing the next six regular international home matches abroad. It is also required where one team's home location is in a war zone or at high risk of terrorism, or if the visiting team is prevented from travelling to (one of) their opponent's regular stadium(s) for political reasons. The latter consideration is uncommon because governing bodies typically implement measures to prevent national teams from jurisdictions with the most serious political disputes (for example, Spain and Gibraltar or Serbia and Kosovo) from being drawn in the same group, but it does happen - for example, the Ukraine-Kosovo qualifier game for the 2018 World Championships was held in Krakow, Poland, because the Ukraine does not recognize Kosovo and does not admit Kosovar nationals to its territory. In all such cases, the match is still treated as a "home" match for such purposes as implementing the away goals rule.

Baseball
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 include the season's two tiebreaker games, which are officially counted as part of the regular season, but 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.

Basketball
In the 2017–18 NBA regular season, the home team won 712 games (58%), and the away team won 518 games (42%).


 * The team with the best overall record, the Houston Rockets, finished 65–17, going 34–7 at home and 31–10 away. In all, 52% of their wins were at home, and 59% of their losses were on the road.
 * The Toronto Raptors had the same home record as the Rockets, but went 25–16 away. This meant that 58% of their wins were at home, and nearly 70% of their losses were away.
 * The season's largest differential between home and road records was that of the San Antonio Spurs. Their home record was only one game worse than that of the Rockets and Raptors, at 33–8, but their road record was 14–27. The Spurs had 70% of their wins at home, and 77% of their losses were away.
 * The only team with a better record on the road than at home was the Phoenix Suns, who had the worst record in the league at 21–61. Their home and road records were separated by only one game (10–31 home, 11–30 away).

Association football
In the 2016–17 Premier League, the home team won 187 matches (49%), the away team won 109 matches (29%), and teams drew in 84 matches (22%), however this is an aberration as Home advantage has been steadily declining for over a century.


 * Manchester City FC had 23 wins, 9 draws and 6 losses. They had 48% of their wins at home, and 83% of their losses away.
 * Burnley FC had 11 wins, 7 draws and 20 losses. They had 91% of their wins at home, and 70% of their losses away.