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Batting average is a statistic in cricket, baseball, and softball that measures the performance of cricket batsmen and baseball hitters. The two statistics are related in that baseball averages are directly descended from the concept of cricket averages.^{[1]}
In cricket, a player's batting average is the total number of runs he has scored divided by the number of times he has been out. Since the number of runs a player scores and how often he gets out are primarily measures of his own playing ability, and largely independent of his team mates, batting average is a good metric for an individual player's skill as a batsman. The number is also simple to interpret intuitively. If all the batsman's innings were completed (i.e. he was out every innings), this is the average number of runs he scores per innings. If he didn't complete all his innings (i.e. some innings he finished not out), this number is an estimate of the unknown average number of runs he scores per innings. Batting average has been used to gauge cricket players' relative skills since the 18th century.
Most players have career batting averages in the range of 20 to 40. This is also the desirable range for wicketkeepers, though some fall short and make up for it with keeping skill. Until a substantial increase in scores in the 21st century due to improved bats and smaller grounds among other factors, players who sustained an average above 50 through a career were considered exceptional, and before the development of the heavy roller in the 1870s an average of 25 was considered very good.^{[2]}
Career records for batting average are usually subject to a minimum qualification of 20 innings played, in order to exclude batsmen who have not played enough games for their skill to be reliably assessed. Under this qualification, the highest Test batting average belongs to Australia's Sir Donald Bradman, with 99.94. Given that a career batting average over 50 is exceptional, and that only four other players have averages over 60, this is an outstanding statistic. The fact that Bradman's average is so far above that of any other cricketer has led several statisticians to argue that, statistically at least, he was the greatest sportsman in any sport.^{[3]}
Batting averages in One Day International (ODI) cricket tend to be lower than in Test cricket, because of the need to score runs more quickly and take riskier strokes and the lesser emphasis on building a large innings. It should also be remembered, especially in relation to the ODI histogram above, that there were no ODI competitions when Bradman played.
If a batsman has been got out every single innings, then his total number of runs scored divided by the number of times he has been out gives exactly the average number of runs he scores per innings. However, for a batsman with innings which have finished not out, this statistic is only an estimate of the average number of runs he scores per innings  the true average number of runs he scores per innings is unknown as it is not known how many runs he would have scored if he could have completed all his not out innings. If his scores have a geometric distribution then total number of runs scored divided by the number of times out is the maximum likelihood estimate of his true unknown average.^{[4]}
Batting averages can be strongly affected by the number of not outs. For example Phil Tufnell, who was noted for his poor batting,^{[5]} has an apparently respectable ODI average of 15 (from 20 games), despite a highest score of only 5 not out, as he scored an overall total of 15 runs from 10 innings, but was out only once.^{[6]}
A different, and more recently developed, statistic which is also used to gauge the effectiveness of batsmen is the strike rate. It measures a different concept however – how quickly the batsman scores (number of runs from 100 balls) – so it does not supplant the role of batting average. It is used particularly in limited overs matches, where the speed at which a batsman scores is more important than it is in firstclass cricket.
(Source: Cricinfo Statsguru 28 February 2014)
Rank  Batsman  Tests  Innings  N.O.  Runs  Highest  Ave^{[7]}  Career dates 

1  D. G. Bradman  52  80  10  6996  334  99.94  1928–1948 
2  R. G. Pollock  23  41  4  2256  274  60.97  1963–1970 
3  G. A. Headley  22  40  4  2190  270*  60.83  1930–1954 
4  H. Sutcliffe  54  84  9  4555  194  60.73  1924–1935 
5  E. Paynter  20  31  5  1540  243  59.23  1931–1939 
6  C. A. Pujara  19  32  4  1650  206*  58.92  2010–Present 
7  K. F. Barrington  82  131  15  6806  256  58.67  1955–1968 
8  E.D. Weekes  48  81  5  4455  207  58.61  1948–1958 
9  W. R. Hammond  85  140  16  7249  336*  58.45  1927–1947 
10  K. C. Sangakkara  122  209  17  11151  319  58.07  2000–Present 
Table shows players with at least 20 innings completed.
* denotes not out.
For more comprehensive statistics see List of cricket batting averages.
In baseball, the batting average (BA) is defined by the number of hits divided by at bats. It is usually reported to three decimal places and pronounced as if it were multiplied by 1,000: a player with a batting average of .300 is "batting threehundred."
Henry Chadwick, an English statistician raised on cricket, was an influential figure in the early history of baseball. In the late 19th century he adapted the concept behind the cricket batting average to devise a similar statistic for baseball. Rather than simply copy cricket's formulation of runs scored divided by outs, he realized that hits divided by at bats would provide a better measure of individual batting ability. This is due to the fact that while in cricket, scoring runs is almost entirely dependent on one's own batting skill, in baseball it is largely dependent on having other good hitters on one's team. Chadwick noted that hits are independent of teammates' skills, so used this as the basis for the baseball batting average. His reason for using at bats rather than outs is less obvious, but it leads to the intuitive idea of the batting average being a percentage reflecting how often a batter gets on base, whereas in contrary, hits divided by outs is not as simple to interpret in real terms.
In modern times, a season batting average higher than .300 is considered to be excellent, and an average higher than .400 a nearly unachievable goal. The last player to do so, with enough plate appearances to qualify for the batting championship, was Ted Williams of the Boston Red Sox, who hit .406 in 1941, though the best modern players either threaten to or actually do achieve it occasionally, if only for brief periods of time. There have been numerous attempts to explain the disappearance of the .400 hitter, with one of the more rigorous discussions of this question appearing in Stephen Jay Gould's 1996 book Full House.
Ty Cobb holds the record for highest career batting average with .366, 8 points higher than Rogers Hornsby who has the second highest average in history at .358. The record for lowest career batting average for a player with more than 2,500 atbats belongs to Bill Bergen, a catcher who played from 1901 to 1911 and recorded a .170 average in 3,028 career atbats. The modernera record for highest batting average for a season is held by Napoleon Lajoie, who hit .426 in 1901, the first year of play for the American League. The modernera record for lowest batting average for a player that qualified for the batting title is held by Rob Deer, who hit .179 in 1991. While finishing six plate appearances short of qualifying for the batting title, Adam Dunn of the Chicago White Sox hit .159 for the 2011 season, twenty points (and 11.2%) lower than the record. The highest batting average for a rookie was .408 in 1911 by Shoeless Joe Jackson.
For nonpitchers, a batting average below .230 is often considered poor, and one below .200 is usually unacceptable. This latter level is sometimes referred to as "The Mendoza Line", named for Mario Mendoza, a stellar defensive shortstop whose defensive capabilities just barely made up for his offensive shortcomings. The league batting average in Major League Baseball for 2004 was just higher than .266, and the alltime league average is between .260 and .275.
Sabermetrics, the study of baseball statistics, considers batting average a weak measure of performance because it does not correlate as well as other measures to runs scored, thereby causing it to have little predictive value. Batting average does not take into account walks or power, whereas other statistics such as onbase percentage and slugging percentage have been specifically designed to measure such concepts. Adding these statistics together form a player's Onbase plus slugging or "OPS". This is commonly seen as a much better, though not perfect, indicator of a player's overall batting ability as it is a measure of hitting for average, hitting for power and drawing bases on balls.
In 1887, Major League Baseball counted bases on balls as hits. The result of this was skyrocketed batting averages, including some near .500, and the experiment was abandoned the following season.
The Major League Baseball batting averages championships (often referred to as "the batting title") is awarded annually to the player in each league who has the highest batting average. Ty Cobb holds the MLB (and American League) record for most batting titles, officially winning 11 in his pro career.^{[1]} The National League record of 8 batting titles is shared by Honus Wagner and Tony Gwynn. Most of Cobb's career and all of Wagner's career took place in what is known as the DeadBall Era, which was characterized by higher batting averages and much less power, whereas Gwynn's career took place in the LiveBall Era.
To determine which players are eligible to win the batting title, the following conditions have been used over the sport's history:^{[8]}
From 1967 to the present, if the player with the highest average in a league fails to meet the minimum plateappearance requirement, the remaining atbats until qualification (e.g., 5 ABs, if the player finished the season with 497 plate appearances) are hypothetically considered hitless atbats; if his recalculated batting average still tops the league, he is awarded the title. This is officially called Rule 10.22(a), but it is also known as the Tony Gwynn rule because the Padres' legend won the batting crown in 1996 with a .353 average on just 498 plate appearances (i.e., was four shy). Gwynn was awarded the title since he would have led the league even if he'd gone 0for4 in those missing plate appearances. His average would have dropped to .349, five points better than secondplace Ellis Burks' .344.^{[9]} In 2012, a onetime amendment to the rule was made to disqualify Melky Cabrera from the title. Cabrera requested that he be disqualified after serving a suspension that season for a positive testosterone test. He had batted .346 with 501 plate appearances, and the original rule would have awarded him the title over San Francisco Giants teammate Buster Posey, who won batting .336.^{[10]}^{[11]}
#  Player  Avg ^{[12]}  Team(s)  Year(s) 

1  Ty Cobb  .366  Detroit, Philadelphia (AL)  1905–28 
2  Rogers Hornsby  .358  St. Louis (NL), New York (NL), Boston (NL), Chicago (NL), St. Louis (NL), St. Louis (AL)  1915–37 
3  Shoeless Joe Jackson  .356  Philadelphia (AL), Cleveland, Chicago (AL)  1908–1920 
4  Lefty O'Doul  .349  New York (AL), Boston (AL), New York (NL), Philadelphia (NL), Brooklyn  1919–23, 1928–34 
5  Ed Delahanty  .346  Philadelphia (NL), Cleveland (PL), Philadelphia (NL), Washington  1888–1903 
6  Tris Speaker  .345  Boston (AL), Cleveland, Washington (AL), Philadelphia (AL)  1907–28 
7  Ted Williams  .344  Boston (AL)  1939–42, 1946–60 
7  Billy Hamilton  .344  Kansas City (AA), Philadelphia (NL), Boston (NL)  1888–1901 
9  Dan Brouthers  .342  Troy, Buffalo, Detroit (NL), Boston (NL), Boston (PL), Brooklyn (NL), Baltimore (NL), Louisville, Philadelphia (NL), New York (NL)  1879–96, 1904 
9  Babe Ruth  .342  Boston (AL), New York (AL), Boston (NL)  1914–35 
Following from usage in cricket and baseball, batting average has come to be used for other statistical measures of performance and in the general usage on how a person did in a wide variety of actions.
An example is the Internet Archive, which uses the term in ranking downloads. Its "batting average" indicates the correlation between views of a description page of a downloadable item, and the number of actual downloads of the item. This avoids the effect of popular downloads by volume swamping potentially more focused and useful downloads, producing an arguably more useful ranking.

