The Duckworth–Lewis–Stern (DLS) method is a mathematical formula used in limited-overs cricket to set a fair target score for the team batting second when the match is interrupted by weather or other delays. It accounts for the fact that both teams have two key resources to score runs: the number of overs (or balls) remaining and the number of wickets in hand
How the DLS Method Works
- Resources Concept : Each team starts with 100% resources, which means 50 overs and 10 wickets (in a standard ODI). As the innings progresses, these resources decrease as overs are bowled and wickets fall. The ability to score runs depends on the combination of these remaining resources
- Resource Percentage Table : The DLS method uses a pre-calculated table or computer model that converts any combination of overs left and wickets remaining into a "resources remaining" percentage. For example, if a team has 25 overs left and 5 wickets in hand, the table gives the percentage of resources still available to them
- Adjusting Targets : When a match is interrupted, the target for the team batting second is adjusted proportionally based on the resources available to both teams. The formula used is:
Team 2’s par score=Team 1’s score×Team 2’s resourcesTeam 1’s resources\text{Team 2's par score}=\text{Team 1's score}\times \frac{\text{Team 2's resources}}{\text{Team 1's resources}}Team 2’s par score=Team 1’s score×Team 1’s resourcesTeam 2’s resources
This means the target is scaled according to how many resources each team had or lost due to interruptions
- Consideration of Wickets and Timing : The method recognizes that losing overs later in the innings typically has a bigger impact than losing them early, because teams tend to score faster towards the end. Also, losing wickets reduces scoring potential, so the fewer wickets a team has, the fewer runs they are expected to score in the remaining overs
- Limitations : The method does not consider the specific batsmen dismissed or yet to bat, only the number of wickets lost
Summary
The DLS method ensures fairness by quantifying the scoring potential of a team based on their remaining overs and wickets, then adjusting the target score accordingly when interruptions occur. It is widely accepted and used in international cricket today as the standard for rain-affected matches
In essence, the DLS method balances the resources lost due to interruptions to maintain the same level of difficulty for the chasing team as was originally intended for the match.
