Duckworth-Lewis-Stern: 2 Brit statisticians, 1 American professor behind cricket’s winning formula when it rains

Meet the men behind the Duckworth-Lewis-Stern system that featured prominently during the India-Pakistan match over the weekend.

The Duckworth-Lewis-Stern (DLS) system is the GST of cricket. Relatively simple on paper, it involves complex calculations in real life. Cricketers themselves do not fully grasp the DLS, though most of them accept that in the absence of anything better, it is the fairest way of conducting weather-interrupted matches.

During the India-Pakistan match at the World Cup, commentators Virender Sehwag, Sachin Tendulkar and Sourav Ganguly, none of whom were ever Fields Medal contenders, admitted being clean bowled by the rule. Sehwag cleverly put Ganguly on the spot. Had Ganguly, by virtue of being captain, figured out the DLS system?


Without looking at Sehwag, Ganguly dead-panned, “It will take an entire day to try to explain it.” Here is a very basic definition of DLS. Earlier, if weather interrupted a match, the target would be revised simply based on the run rate at which the first team had scored. Under DLS, even wickets lost by the team batting second are taken into consideration.

The men behind the maths Frank Duckworth, 79, is a statistician who was the editor of the British Royal Statistical Society Journal. His lone cricket achievement was 11 not out in a school game. And he once rented a room in the house of John Lennon’s aunt Mimi.

Tony Lewis, 77, is a mathematician with degrees in mathematics and statistics from Shef field University. He retired as a lecturer of Quantitative Research Methods from Oxford Brookes University. Duckworth and Lewis are both MBEs (Order of the Member of the British Empire).

Steven Stern, in charge of updating and implementing the Duckworth-Lewis method after the retirement of the founders, is an American who had not heard of cricket for the longest time. He got acquainted with the game when he met Australians during his student days at Stanford University. Stern then moved to Australia, and his ties with the sport strengthened. He is currently a professor of Data Science at Bond University, Gold Coast.

How the method came to be
If not for 12 minutes of rain in Sydney in 1992, DLS may not have existed. But the prevalent rain rule during the 1992 World Cup made a mockery of the semi-final between England and South Africa, triggering a desperate search for a better method. England batted first and scored 252. In response, South Africa were 231 for six, needing just 22 off 13 balls, when rain stopped play for 12 minutes.

South Africa’s target was revised as per the existing method — the MPO (Most Productive Overs) to an impossible 21 from one ball (the scoreboard wrongly flashed 22). South African players and the game’s followers and custodians were outraged. Among those who made an anguished plea for the weather rules to be changed was the respected cricket writer Christopher Martin Jenkins. And listening to CMJ on radio was a statistician named Frank Duckworth.

“I recall hearing Christopher Martin-Jenkins on radio saying, ‘Surely someone, somewhere could come up with something better’ and I soon realised that it was a mathematical problem that required a mathematical solution,” Duckworth said in an interview.

Lewis soon came on board and the Duckworth-Lewis method was accepted by the International Cricket Council (ICC) in 1997. Such are the variables of the sport, though, that it hasn’t always gone down well with players and fans. In fact, an Indian engineer named V Jayadevan has developed his own system called the VJD, which, he says, is better than DLS. For now, though, DLS remain the ABC of resolving weather-affected matches.