How Do You Figure out a Batting Average?
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 by the cricket statistic. In cricket, a player’s batting average is the total number of runs they have scored divided by the number of times they have been out.
Since the number of runs a player scores and how often they get out are primarily measures of their own playing ability, and largely independent of their 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 the entire batsman’s innings were completed (i.e. they were out every innings), this is the average number of runs they score per innings. If they did not complete all their innings (i.e. some innings they finished not out), this number is an estimate of the unknown average number of runs they score 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 well.
All-rounders who are more prominent bowlers than batsmen average 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 or completed, 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. As at 21 October 2016, Adam Voges of Australia has recorded an average of 72.75 from 27 innings played, but only 20 innings completed.
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 dismissed in every single innings, then their total number of runs scored divided by the number of times they have been out gives exactly the average number of runs they score 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 they score per innings – the true average number of runs they score per innings is unknown as it is not known how many runs they would have scored if they could have completed all their not out innings. If their scores have a geometric distribution then total number of runs scored divided by the number of times out is the maximum likelihood estimate of their 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, 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.
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 over matches, where the speed at which a batsman scores is more important than it is in first-class cricket.