Duckworth-Lewis-Stern Method in Cricket

The Duckworth-Lewis-Stern (DLS) method is a mathematical formula used in limited-overs cricket to calculate revised targets when rain or other interruptions reduce the overs available to one or both teams. It replaced earlier, simpler systems that were widely seen as unfair.

Why DLS Was Needed

Before DLS, rain-revised targets were set using crude methods — the most notorious was the 'highest scoring overs' rule, which penalised teams that had lost overs during their powerplay or when they had wickets in hand. DLS accounts for two resources simultaneously: overs remaining and wickets remaining.

The Core Principle

DLS treats a team's resources as a combination of overs and wickets. Having all 10 wickets with 20 overs remaining is a different resource to having 5 wickets with 20 overs remaining — the first team has more potential. DLS tables assign a percentage resource value to every combination and use them to set fair targets.

How DLS Calculates Revised Targets

1. Note the resources (overs + wickets) available to Team 1 at the start and when interrupted.
2. Calculate the proportion of resources lost by Team 1 due to interruptions.
3. Apply the same resource fraction to Team 2's target.
4. If Team 2 has more resources than Team 1, their target is scaled up (above Team 1's score).
5. If fewer resources, the target is reduced proportionally.

Famous DLS Controversies

• 1992 Cricket World Cup semi-final (England vs South Africa): the simpler 'most economical overs' method produced a famously absurd revised target of 22 from 1 ball — this was one of the key triggers for developing DLS.
• DLS targets in T20 are often seen as too easy when rain arrives in the first few overs.