The Duckworth Lewis system has come in for criticism recently. It was interesting to read some of the comments from captains, coaches and the press:
- Players and spectators do not understand it
- It is complicated to use
- It isn’t transparent
- It is unfair
- It is counter intuitive
But what is the truth?
Do we need it and what are the options?
In limited over matches most people would probably agree that providing sufficient time for both sides to receive 50-overs is preferable. Fair, simple to understand and to apply: Just score more runs than the opposition to win, even if it takes days or weeks to get a result.
But for most cricket we do not have the luxury of reserve days and floodlights etc so we need a mechanism to achieve a result. (Other than a draw or no result). And so the concept of reducing the overs in an innings to at most a minimum number of overs, was introduced. But who wins if the two innings are of different lengths?
Initially this was based on comparative run rates. This was simple to understand and easy to calculate mentally, although on some occasions a calculator was required if the rates were very close. All a side had to do was stay ahead of the run rate to win when batting second. This system generally favours a team batting second, but there was a small concession, as the bowlers’ limit was not reduced below the nominal ten overs.
So on a day when it was expected that the weather would reduce the overs the toss becomes crucial. For example, if the first team scores 250 in 50-overs and it rains during the tea interval, then it may have only to chase 126 to win in 25-overs. This is not very fair to the team batting first.
In an attempt to produce a fair result many methods have been proposed. Details are available here:
http://cricketarchive.com/Miscellaneous/Rain_Rule_Methods.html
One of them, the “best-scoring overs" method was used in the 1992 World Cup. South Africa required 22 runs from 13 balls when the rain arrived. On resumption the target became 21 runs from just one ball!
And so the search began for a fairer system
The Duckworth Lewis method, which was created by Frank Duckworth and Tony Lewis, was first used in international cricket in the second game of the 1996/7 Zimbabwe versus England series. The ICC subsequently adopted it in 2001.
The kernel of the Duckworth Lewis method is the 'resources” which each team has. A team has two resources: wickets and overs. How it uses these determines their final score. And if it rains a team will lose overs and hence the opportunity to score runs, provided they have wickets in hand. This method adjusts a team’s score for this loss of overs.
Since the method was introduced it has undergone a number of adjustments and refinements as more match data became available, to reflect new scoring patterns and changes made to playing conditions e.g. power plays.
There have been a number of well-publicised “incidents” using Duckworth Lewis. The headlines are often “Duckworth Lewis catastrophe”, “Duckworth Lewis chaos” etc. implying the method is flawed.
But two very public cases indicate that it is a problem of interpretation by the users and not a problem with the method.
In the 2003 World Cup in South Africathe hosts' final group match against Sri Lanka was halted by rain. Rain had earlier affected the match and South Africathought they were winning as batsman Mark Boucher defended what became the last delivery of the match. South Africaskipper Shaun Pollock read the figures on the Duckworth Lewis printout as the target score (runs to win). However the figures are “par” scores” which meant the match was tied.
And more recently in the West Indies match v England on 20th March the West Indies coach John Dyson called his players in for bad light, believing that his team was winning by one run under the Duckworth Lewis method. He had not taken into account that a wicket had just fallen and misread the printout. The West Indies were two runs short of their target, giving England a surprise one-run victory.
The Duckworth Lewis method is relatively simple to apply andis widely acclaimed as the fairest of the many solutions that have been tried to decide the winner in weather-interrupted matches. Statistically the team that bats first wins 52% of matches in which there are no interruptions. Where a match is interrupted and overs are reduced in either or both innings and Duckworth Lewis is used, the first batting team still wins 52% of matches.
Captains and scorers are provided with a printout of “par scores” using a simple Duckworth Lewis computer program. Well-appointed and progressive clubs provide special announcements on scoreboards and PA systems to ensure spectators and indeed players clearly know the state of the game. There is in place a special protocol for this.
So there should be no excuses for coaches or captains to get it wrong. Perhaps they should all heed the old adage:
Fail to prepare – prepare to fail!
