Is Duckworth Lewis Method a Right Process To Select the Winner ?
The Chennai Super Kings have beaten Kolkata Knight Riders by 10 wickets as per the D/L method in a storm-hit IPL tie at the Eden Gardens in Kolkata on 18.05.2008.
The game came to a halt due to a storm followed by rains when Super Kings were 55 without any loss of wicket in eight overs. According to the D/L method, they were 3 runs ahead of the revised target of 52 runs. Chennai Super Kings openers Stephen Fleming (32) and Parthiv Patel (19) remained unbeaten.
So What is This Duckworth Lewis method or D/L method? Is it a right process to select the winner of a canceled match?
The Duckworth Lewis method or D/L method is a set of formulas and tables created by Frank Duckworth and Tony Lewis. The method was adopted by the International Cricket Council (ICC) in 1999 to address the problem of delayed one-day cricket matches for reasons of rain, poor light and floodlight failures although it has also been used in events that have been shortened due to crowd problem, sandstorms and even snowstorms.
A simple example of the D/L method being applied was the first One Day International (ODI) between India and Pakistan in their 2006 ODI series. India batted first, and were all out in the 49th over for 328. Pakistan, batting second, were 7 wickets down for 311 when bad light stopped play after the 47th over.
In this example, Pakistan's target had the match continued was 18 runs in as many balls, with three wickets in hand. Considering the overall scoring rate throughout the match, this is a target most teams would be favored to achieve. And indeed, application of the D/L method resulted in a target score of 304 at the end of the 47th over, with the officially listed result as "Pakistan won by 7 runs (D/L Method)"
Scoring potential as a function of wickets and overs.
The essence of the D/L method is 'resources'. Each team is taken to have two 'resources' to use to make as many runs as possible: the number of overs they have to receive; and the number of wickets they have in hand. At any point in any innings, a team's ability to score more runs depends on the combination of these two resources. Looking at historical scores, there is a very close correspondence between the availability of these resources and a team's final score, a correspondence which D/L exploits.
Using a published table which gives the percentage of these combined resources remaining for any number of overs (or, more accurately, balls) left and wickets lost, the target score can be adjusted up or down to reflect the loss of resources to one or both teams when a match is shortened one or more times. This percentage is then used to calculate a target (sometimes called a 'par score') that is usually a fractional number of runs. If the second team passes the target then the second team is taken to have won the match; if the match ends when the second team has exactly met (but not passed) the target (rounded down to the next integer) then the match is taken to be a tie.
The D/L method is relatively simple to apply, but requires a published reference table and some simple mathematical calculation (or use of a computer). As with most non-trivial statistical derivations, however, the D/L method can produce results that are somewhat counterintuitive, and the announcement of the derived target score can provoke a good deal of second-guessing and discussion amongst the crowd at the cricket ground. This can also be seen as one of the method's successes, adding interest to a "slow" rain-affected day of play.
Applied to 50 over matches, each team has to face at least 20 overs before D/L can decide the game. In Twenty20 games, each side has to face at least 5 overs.
The D/L method was devised by two English statisticians, Frank Duckworth and Tony Lewis, originating from an undergraduate final-year project at the University of the West of England. It was first used in international cricket in the second game of the 1996/7 Zimbabwe versus England One Day International series, which Zimbabwe won by 7 runs, and was formally adopted by the International Cricket Council in 2001 as the standard method of calculating target scores in rain shortened one-day matches.
Various different methods had been previously used to achieve the same task, including run-rate ratios, the score that the first team had achieved at the same point in their innings, and targets derived by totaling the best scoring overs in the initial innings. All of these methods have flaws that are easily exploitable. For example, run-rate ratios do not account for how many wickets the team batting second have lost, but simply reflect how quickly they were scoring at the point the match was interrupted; thus, if a team felt a rain stoppage was likely, they could attempt to force the scoring rate without regard for the corresponding highly likely loss of wickets, skewing the comparison with the first team. Notoriously, the "best-scoring overs" method, used in the 1992 Cricket World Cup, left the South African cricket team requiring 21 runs from one ball (when the maximum score from any one ball is generally six runs). Prior to a brief rain interruption, South Africa was chasing a target of 22 runs from 13 balls - which was difficult but at least attainable - but the possibility of an exciting conclusion to the game was destroyed when the team's target was reduced by only one run, to be scored off 12 fewer balls. The D/L method removes - or at least normalises - this flaw: in this match, the revised D/L target would have been four runs to tie or five to win from the final ball.
The published table that underpins the D/L method is regularly updated, most recently in 2004, as it became clear that one-day matches were achieving significantly higher scores than in previous decades, affecting the historical relationship between resources and runs.
At the same time as this update, the D/L method was also split into a Professional Edition and a Standard Edition.[5] The main difference is that while the Standard Edition preserves the use of a single table and simple calculation – suitable for use in any one-day cricket match at any level – the Professional Edition uses substantially more sophisticated statistical modeling, and requires the use of a computer. The Professional Edition has been in use in all international one-day cricket matches since early 2004.
The D/L method has been criticised based on the fact that wickets are (necessarily) a much more heavily weighted resource than overs, leading to the observation that if teams are chasing big targets, and there is the prospect of rain, a winning strategy could be to not lose wickets and score at what would seem to be a "losing" rate (e.g. if the asking rate was 6.1, it could be enough to score at 4.75 an over for the first 20-25 overs).
Another criticism is that the D/L method does not account for changes in the number of overs during which field restrictions are in place.
More common informal criticism from cricket fans and journalists of the D/L method is that it is overly complex and can be misunderstood.
The game came to a halt due to a storm followed by rains when Super Kings were 55 without any loss of wicket in eight overs. According to the D/L method, they were 3 runs ahead of the revised target of 52 runs. Chennai Super Kings openers Stephen Fleming (32) and Parthiv Patel (19) remained unbeaten.
So What is This Duckworth Lewis method or D/L method? Is it a right process to select the winner of a canceled match?
The Duckworth Lewis method or D/L method is a set of formulas and tables created by Frank Duckworth and Tony Lewis. The method was adopted by the International Cricket Council (ICC) in 1999 to address the problem of delayed one-day cricket matches for reasons of rain, poor light and floodlight failures although it has also been used in events that have been shortened due to crowd problem, sandstorms and even snowstorms.
Example
A simple example of the D/L method being applied was the first One Day International (ODI) between India and Pakistan in their 2006 ODI series. India batted first, and were all out in the 49th over for 328. Pakistan, batting second, were 7 wickets down for 311 when bad light stopped play after the 47th over.
In this example, Pakistan's target had the match continued was 18 runs in as many balls, with three wickets in hand. Considering the overall scoring rate throughout the match, this is a target most teams would be favored to achieve. And indeed, application of the D/L method resulted in a target score of 304 at the end of the 47th over, with the officially listed result as "Pakistan won by 7 runs (D/L Method)"
Theory
Scoring potential as a function of wickets and overs.
The essence of the D/L method is 'resources'. Each team is taken to have two 'resources' to use to make as many runs as possible: the number of overs they have to receive; and the number of wickets they have in hand. At any point in any innings, a team's ability to score more runs depends on the combination of these two resources. Looking at historical scores, there is a very close correspondence between the availability of these resources and a team's final score, a correspondence which D/L exploits.
Using a published table which gives the percentage of these combined resources remaining for any number of overs (or, more accurately, balls) left and wickets lost, the target score can be adjusted up or down to reflect the loss of resources to one or both teams when a match is shortened one or more times. This percentage is then used to calculate a target (sometimes called a 'par score') that is usually a fractional number of runs. If the second team passes the target then the second team is taken to have won the match; if the match ends when the second team has exactly met (but not passed) the target (rounded down to the next integer) then the match is taken to be a tie.
Application
The D/L method is relatively simple to apply, but requires a published reference table and some simple mathematical calculation (or use of a computer). As with most non-trivial statistical derivations, however, the D/L method can produce results that are somewhat counterintuitive, and the announcement of the derived target score can provoke a good deal of second-guessing and discussion amongst the crowd at the cricket ground. This can also be seen as one of the method's successes, adding interest to a "slow" rain-affected day of play.
Applied to 50 over matches, each team has to face at least 20 overs before D/L can decide the game. In Twenty20 games, each side has to face at least 5 overs.
History
The D/L method was devised by two English statisticians, Frank Duckworth and Tony Lewis, originating from an undergraduate final-year project at the University of the West of England. It was first used in international cricket in the second game of the 1996/7 Zimbabwe versus England One Day International series, which Zimbabwe won by 7 runs, and was formally adopted by the International Cricket Council in 2001 as the standard method of calculating target scores in rain shortened one-day matches.
Various different methods had been previously used to achieve the same task, including run-rate ratios, the score that the first team had achieved at the same point in their innings, and targets derived by totaling the best scoring overs in the initial innings. All of these methods have flaws that are easily exploitable. For example, run-rate ratios do not account for how many wickets the team batting second have lost, but simply reflect how quickly they were scoring at the point the match was interrupted; thus, if a team felt a rain stoppage was likely, they could attempt to force the scoring rate without regard for the corresponding highly likely loss of wickets, skewing the comparison with the first team. Notoriously, the "best-scoring overs" method, used in the 1992 Cricket World Cup, left the South African cricket team requiring 21 runs from one ball (when the maximum score from any one ball is generally six runs). Prior to a brief rain interruption, South Africa was chasing a target of 22 runs from 13 balls - which was difficult but at least attainable - but the possibility of an exciting conclusion to the game was destroyed when the team's target was reduced by only one run, to be scored off 12 fewer balls. The D/L method removes - or at least normalises - this flaw: in this match, the revised D/L target would have been four runs to tie or five to win from the final ball.
Updates
The published table that underpins the D/L method is regularly updated, most recently in 2004, as it became clear that one-day matches were achieving significantly higher scores than in previous decades, affecting the historical relationship between resources and runs.
At the same time as this update, the D/L method was also split into a Professional Edition and a Standard Edition.[5] The main difference is that while the Standard Edition preserves the use of a single table and simple calculation – suitable for use in any one-day cricket match at any level – the Professional Edition uses substantially more sophisticated statistical modeling, and requires the use of a computer. The Professional Edition has been in use in all international one-day cricket matches since early 2004.
Criticism
The D/L method has been criticised based on the fact that wickets are (necessarily) a much more heavily weighted resource than overs, leading to the observation that if teams are chasing big targets, and there is the prospect of rain, a winning strategy could be to not lose wickets and score at what would seem to be a "losing" rate (e.g. if the asking rate was 6.1, it could be enough to score at 4.75 an over for the first 20-25 overs).
Another criticism is that the D/L method does not account for changes in the number of overs during which field restrictions are in place.
More common informal criticism from cricket fans and journalists of the D/L method is that it is overly complex and can be misunderstood.
posted by Munna / Rakesh @ 11:59 PM,
1 Comments:
At June 16, 2008 at 7:23 PM,
Terminally Insane said...