A famous formula
How Steve Stern became the custodian of cricket's most famous formula
A famous formula
How Steve Stern became the custodian of cricket's most famous formula
When Steve Stern emailed Frank Duckworth and Tony Lewis about their famous rain-affected cricket formula, he expected little more than a courteous reply. Instead, the exchange would eventually lead the Professor of Data Science to being recognised as the "S" in cricket's DLS (Duckworth-Lewis-Stern) Method and stopped by fans across India.
Steve sent the email in the late-1990s, landing in the inboxes of two statisticians whose work had revolutionised rain-affected cricket. By sheer chance, Frank had been searching for reading material for a plane trip. Steve sees it as another moment in his life where timing worked in his favour, along with studying at Stanford during the rise of computing to arriving in Australia during cricket's golden era. But to anyone who knows Steve’s story, his success is the sum of an unfeigned passion for problem solving, curiosity, and persistence.
What is the DLS method?
The Duckworth-Lewis method is a formula to calculate a revised target score for the team batting second when weather interrupts a limited overs cricket match.
Devised in its original form by two British statisticians, the Duckworth-Lewis method was officially adopted by the International Cricket Council (ICC) in 1999. Australian statistician Steve Stern later enhanced the model, resulting in the Duckworth-Lewis-Stern (DLS) method used in international cricket today.
What is the DLS method?
The Duckworth-Lewis method is a formula to calculate a revised target score for the team batting second when weather interrupts a limited overs cricket match.
Devised in its original form by two British statisticians, the Duckworth-Lewis method was officially adopted by the International Cricket Council (ICC) in 1999. Australian statistician Steve Stern later enhanced the model, resulting in the Duckworth-Lewis-Stern (DLS) method used in international cricket today.
Putting the S in DLS
Cricket was a hot topic when Steve moved from the United States to Australia in 1994. Shane Warne and Steve Waugh were among the household names transforming the Australian cricket team into a powerhouse. And new friends were eager to take Steve to local cricket matches and test his knowledge.
“They said ‘there’s this weird new mathematical thing they’ve just started using, maybe you can figure that out’ and that was the Duckworth-Lewis method,” he says.
Steve made it his next research project.
“I reversed engineered the whole thing and theorised how I could improve aspects,” he says.
“I was about to send my paper off to a journal, and thought it would be polite if I sent a free copy to Duckworth and Lewis.
“I thought the most I would get back was ‘good luck with your research’.”
Steve was surprised to learn Frank read his entire paper, and was impressed with his work, despite deciding Steve’s suggestions were too complicated to apply in live games.
Another component of Steve’s work caught his attention though. He had been recording what happened on every ball during a professional cricket match — a database he maintains to this day.
“Frank was working on a rating system of the best teams and players and asked if he could use my data,” Steve says.
Steve happily shared the data, beginning a collaboration that would span decades.
“Frank was one of the most generous academics I've ever met,” Steve says.
As cricket evolved and scores grew higher, Frank and Tony realised they needed to expand their famous method beyond a pencil and paper calculation.
“They had no experience in programming in Windows, but I did,” Steve says.
The pair turned to Steve to help bring their system into a new era. Before long, he was responsible for incorporating every change and refinement into the program that underpinned the method.
“Anything they did to change or modify their approach had to be incorporated back into the program,” Steve says.
“Since I was the only one who knew how to run the program, that became my job.”
By 2006, Steve had become the method's official programmer. As Duckworth and Lewis moved into retirement, conversations turned to who would carry their work forward. Steve took on that responsibility just as Twenty20 cricket was transforming the sport, exposing challenges the original method wasn’t designed to address.
Drawing on the growing volume of data from the game's newest format, Steve developed refinements to help the method evolve with modern cricket. The International Cricket Council adopted the changes ahead of the 2015 Cricket World Cup, and in 2014 the formula was officially renamed the Duckworth-Lewis-Stern method.
More than a decade after sending an email he never expected to be answered, Steve had become the S in one of cricket's most influential mathematical models.
“It was surreal seeing the revised version adopted around the world,” he says.
“I now go to India and I'm mobbed and it's very strange.”
The making of a mathematician
The odds always pointed to Steve building a life around numbers. He grew up in Silicon Valley with a maths teacher mum and a medical researcher dad.
By Year 6, he was taking advanced maths, by Year 11 he was completing university subjects.
“I just loved puzzles of all kinds,” he says. “I still to this day, every day at lunch, do the New York Times crossword puzzle.”
It was an obvious choice to major in mathematics by the time he enrolled at Stanford University.
After completing his master’s degree in applied statistics in 1987, Steve joined a consulting firm, applying maths to real-world disputes, civil court cases and research problems. The role exposed him to a wide range of industries, including work for tobacco companies seeking alternative explanations for the link between smoking and lung cancer. Still in his early 20s, Steve grew increasingly uncomfortable with the work and yearned to return to the deeper problem solving that initially drew him to the industry.
“It taught me a lot about computer programming. It taught me a lot about dealing with clients, but it didn't actually advance my mathematical knowledge very much,” Steve says.
He returned to Stanford University to pursue a PhD in probability theory, building a reputation as a talented theorist. As he neared the end of his doctorate, an Australian colleague told him about a postdoctoral opportunity at Australian National University. Steve accepted what he intended to be a three-year stint down under.
“I came to Australia and I just couldn't leave,” he says.
The sporting culture, relaxed lifestyle and opportunities for research felt like a natural fit.
From cricket to bushfires: The many applications of data science
Today, Steve splits his time between teaching at Bond University and research projects that come his way. While cricket may have made him famous, it is just one of many problems he has tackled with data. Over the course of his career, he has worked on projects involving Indigenous life expectancy, Australian Customs, bushfire recovery, solar panel safety, and even concussion research.
“There's not a place or an occupation or an industry in the world that doesn't have some data component,” he says.
Regardless of where a puzzle comes from, Steve is driven by the same instinct: a curiosity about how things work and how they might work better.
It's the mindset he now tries to pass on to students.
Not just how to find answers but how to recognise the questions worth asking.
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