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Batting average is a statistic in cricket, baseball, and softball that measures the performance of Batsmen in Cricket and Batters in Baseball. The development of the baseball statistic was influenced from the concept of cricket averages. == Cricket == 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 wicket-keepers, 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.〔See Rae, Simon; W.G. Grace: A Life; p. 26. ISBN 0571178553〕 * All-rounders who are more prominent bowlers than batsmen typically average something between 20 and 30. * 15 and under is typical for specialist bowlers. * A small number of "rabbits" have averaged less than 5 for a complete career, though a player with such an average is a liability unless an ''exceptional'' bowler as Alf Valentine or B. S. Chandrasekhar were. 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. Batting averages in One Day International (ODI) cricket tend to be lower than in Test cricket,〔(– Highest Career Battin Average in ODIs )〕 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 dismissed in 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. Batting averages can be strongly affected by the number of not outs. For example, Phil Tufnell, who was noted for his poor batting,〔(Cricinfo – The Jack of all rabbits )〕 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.〔(Phil Tufnell )〕 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 first-class cricket. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Batting average」の詳細全文を読む スポンサード リンク
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