Many cricket fans scratch their heads and watch as the umpires access the conditions during a rain delay and question what it means for their side and favourite players.
It often seems like Will Hunting would struggle to work out what is happening with the fabled system of the Duckworth-Lewis-Stern Method.
British Statisticians Frank Duckworth and Tony Lewis calculated the formula as runs required with available sources on offer or wickets that have fallen. In 2014 the forefathers of the method chose to retire and Professor Steven Stern took over to oversee the next phase of the method.
The system was adopted in 1997 by the ICC and is implemented when the heavens open and rain starts to eat into the day’s play. The system is used in the shortest formats of the game to give both sides a fair and reasonable way to come to a result when and if play resumes.
What is DLS ? (Duckworth-Lewis-Stern)
In the longest format of the game rain interruptions cause the game to be delayed without altering the game or changing the score to force a result.
In domestic and international fixtures Duckworth-Lewis method is the sure-fire why to determine a score and required runs to achieve a result within a limited set of time. The below graph shows the equation with wickets lost and overs left.
Originally the method average run rate divided by the number of over left for example if the current run rate was 10 and they were on 200 with five overs remaining in the innings when the delay occurred the side would gain an extra 50 runs taking their total to 250.
The method was deemed unfair cause it didn’t take into account wickets and a team’s ability to score at a much higher rate if there were wickets in hand.
The newest version of the match takes into account the number of wickets and the number of overs left in the play of innings. The method of Duckworth Lewis uses a formula to calculate the overs remain divided by innings with a percentage of wickets remaining.
The method also calculates how many overs a bowler can bowl and how long a powerplay should be to scale it to a shorter game. The percentage takes around about 7% from each wicket that falls from the start of play to the fifth wicket and 13% gradually increasing as more wickets fall.
For the system to be at its most effective and according to the ICC a minimum of five over must be bowler and faced to constitute a match. If less than five overs is played by both teams the game will be considered abandoned with teams sharing the points in tournaments.
