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Whenever a match is interrupted by bad weather, an ideal situation would be to replay it another day. But, still what if a similar problem recurs, or in cases like the T20 World Cup where it is impossible to replay such a game? Duckworth-Lewis-Stern (DLS) method was born to cure this impasse.
The name Duckworth-Lewis-Stern incorporates three people who helped develop the mathematical principle of calculating target scores to reach an outcome in a limited-overs cricket match interrupted by bad weather or other circumstances.
While English statisticians Frank Duckworth and Tony Lewis devised the technique in 1997, it has undergone further improvement, in particular, is one by the Australian academician Steve Stern ahead of the 2015 World Cup.
The International Cricket Council appreciates a formula that takes considers all the parameters as possible to get a result that reflects the efforts of the efforts two opposing teams.
The DLS method is, perhaps, the most accurate system used in international cricket. Whenever either team or both of them do not get their full quota of overs, the DSL help get the fair outcome that even punters participating in the India slots would take with no grey of salt.
A team's run average run rate (ARR) is the runs for every over by the whole team across the entire innings so far.
Earlier, the ICC settled such cases using the Average Run Rate (ARR). The chasing side had to match their opponent’s run-rate in the overs it has available.
Suppose team A had made 250 in their 50 overs, equating to 5 runs per over, and teams B’s innings is reduced to 25 overs, team B’s new target would be (5 x 25) + 1 = 126
In the 1987 Cricket World Cup, England vs Sri Lanka, and the third final of the 1988-89 World Series Cup, Australia vs West Indies.
Ahead of the 1992 Cricket World Cup, Australia devised an improved version of ARR, called Most Productive Over.
This version reduced the target number of runs scored by a team in its least productive overs. But again, it did not solve the earlier problem. Instead, it only favored the team batting first. The flaw became bare in the 1992 World Cup semifinal game between England and South Africa.
Unlike the ARR and MPO methods which both failed to factor the resources a team has left, DLS revises the target based on the available wickets and overs. At the start of an innings, each team 100% of its resources, i.e., 50 overs and ten wickets.
DLS expresses the remaining balls and wickets at any point as a percentage. Its formula considers the scoring pattern, which in international matches is derived from compiled ODI and T20, men and women data. The data is updated annually on the 1st of July. So, the DLS evolves as scoring trends change.
The resource curve is exponential as the rate at which a team depletes its resource is not constant during an innings. So, the depletion speed hastens when more wickets are lost and balls consumed.
Team A par score=Team A score*((Team B Resources)/(Team A Resources))
A computer program generates these resource values.
An engineer from Kerala, V. Jayadevan, has argued that the DLS method is statistically inconsistent, producing inflated figures. He presented the VJD approach to the ICC, which never adopted it. The technique, however, features in the Indian domestic cricket.
Because of logistical and scheduling challenges, it is not always possible to resume or replay an abandoned cricket match after a few hours. That’s why there was a need to develop the fairest way of settling such affected one-dayers. There are a few options that the ICC has tried in the past, but for now, the DLS is the preferred one.
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