What is Duckworth-Lewis method – D/L method in Cricket
Indian won the 1st one day internation against New Zealand. However a major factor was the rains and due to which Duckworth-Lewis method (D/L method) was used to reduce the number of overs which has helped India.
What is Duckworth-Lewis method
In Cricket, the Duckworth-Lewis method (D/L method) is a mathematical way to calculate the target score for the team batting second in a one-day cricket or Twenty-20 cricket match interrupted by weather or other circumstance. It is generally accepted to be a fair and accurate method of setting a target score, but as it attempts to predict what would have happened had the game come to its natural conclusion, it generates some controversy. The D/L method was devised by two English statisticians, Frank Duckworth and Tony Lewis and hence it is called Duckworth-Lewis method.
The summary of the D/L method is ‘resources’. Each team is taken to have two ‘resources’ to use to make as many runs as possible:
- the number of overs they have to receive
- the number of wickets they have in hand.
At any point in any innings, a team’s ability to score more runs depends on the combination of these two resources. Looking at historical scores, there is a very close correspondence between the availability of these resources and a team’s final score, a correspondence which D/L exploits.
Using a published table which gives the percentage of these combined resources remaining for any number of overs (or, more accurately, balls) left and wickets lost, the target score can be adjusted up or down to reflect the loss of resources to one or both teams when a match is shortened one or more times. This percentage is then used to calculate a target (sometimes called a ‘par score’) that is usually a fractional number of runs. If the second team passes the target then the second team is taken to have won the match; if the match ends when the second team has exactly met (but not passed) the target (rounded down to the next integer) then the match is taken to be a tie.
The published table that underpins the D/L method is regularly updated, most recently in 2004, as it became clear that one-day matches were achieving significantly higher scores than in previous decades, affecting the historical relationship between resources and runs.
How to use Duckworth-Lewis method to your advantage
Since wickets are (necessarily) a much more heavily weighted resource than overs if your team is chasing big targets, and there is the prospect of rain, a winning strategy could be to not lose wickets and score at what would seem to be a “losing” rate (e.g. if the asking rate was 6.1, it could be enough to score at 4.75 an over for the first 20-25 overs).
D/L method does not account for changes in the proportion of number of overs during which field restrictions are in place compared to a completed match. This is more important as the matches played these days have PowerPlays.
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