What is Duckworth Lewis-Stern Method and how is it calculated ?
Many cricket fans scratch their heads watching the umpires access the conditions during a rain delay and wonder what that means for their team and their favorite players.
It often seems as if Will Hunting is having trouble figuring out what’s happening with the fabled Duckworth-Lewis-Stern method system.
British statisticians Frank Duckworth and Tony Lewis calculated the formula as runs required with available sources on offer or wickets down. In 2014 the forefathers of the method decided to retire and Professor Steven Stern took charge of the next phase of the method.
The system was adopted by the ICC in 1997 and will be implemented when the skies open up and rain begins to eat into the game of the day. The system is used in the shortest formats of the game to give both sides a fair and reasonable way to reach an outcome if and when play resumes.
What is DLS (Duckworth Lewis Star)
In the game’s longest format, rain disruptions cause the game to be delayed without altering the game or changing the score to force a result.
In domestic and international matches, the Duckworth-Lewis method is the sure why to determine a score and required runs to achieve a result within a limited time span. The graph below shows the equation with wickets lost and overs remaining.
Originally the method divided the average run rate by the number of overs remaining, for example if the current run rate was 10 and they were at 200 with five overs left in the innings when the lag occurred the team would have an additional 50 runs win when their total reaches 250.
The method was considered unfair because it did not take into account wickets and a team’s ability to score at a much higher rate when wickets were in hand.
The latest version of the game takes into account the number of wickets and the number of overs remaining in the innings game. Duckworth Lewis’ method uses a formula to calculate overs remaining divided by innings with a percentage of wickets remaining.
The method also calculates how many overs a bowler can bowl and how long a power play should be to scale to a shorter game. The percentage is approximately 7% of each wicket falling from the start of the match to the fifth wicket, and 13% gradually increasing as more wickets fall.
For the system to be most effective, according to the ICC, there must be at least five over bowlers and faceds to form a match. If fewer than five overs are played by either team, the match is considered abandoned, with teams sharing points in tournaments.