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(Note: throughout the following, the side which bats first is called Team 1 and the side batting second is called Team 2.)

1. Why should Team 2 sometimes be set the task of scoring more runs than were made by Team 1 when they have the same number of overs to face?

When the interruption occurs during the first innings, so that the match is shortened to one of fewer overs per side than it was at its start, Team 1 are usually more disadvantaged than Team 2. Before the stoppage they had been pacing their innings in the expectation of receiving say 50 overs and would not have taken the risks of scoring as fast as they would have done had they known their innings was to be shortened. Team 2, on the other hand, know from the start of their innings that they have the reduced number of overs and can pace their entire innings accordingly. Team 2 are set a higher target to compensate Team 1 for this disadvantage.

Consider, for example, when Team 1 have batted for 40 of an intended 50-over innings and then rain washes out the rest of their innings and there is just time for Team 2 to receive 40 overs. If they had wickets in hand, Team 1 might have expected to make around 60 or 70 in those final 10 overs. But Team 2 know they have only 40 overs to receive from the moment they start their innings. The average score in a 40-over innings is only 20 to 25 less than that made in 50 overs, so Team 1's loss is typically 40-45 runs greater than Team 2's and the target is raised by about this amount.

The necessity to set a higher target for Team 2 arises from the regulations for most competitions which require that lost overs are, where possible, divided equally between the two sides. It would be possible to compensate Team 1 for their disadvantage by allowing them to face more overs than Team 2 and in this way the latter need not be set an enhanced target, but this would require a complicated calculation and would reduce the scope for accommodating further stoppages. Because of these disadvantages, cricket authorities have preferred to stay with the present regulations.

2. Why should this apply when Team 1 have been bowled out?

In limited-overs cricket no distinction is made between the two ways in which an innings is closed, using up all the overs or losing all ten wickets. In both cases the team have used up all the resources of their innings. In an uninterrupted innings, there is no difference between Team 1's score of 250, for instance, whether it were 250 for 3 wickets in 50 overs or whether it were 250 all out in 47 overs. Similarly in an interrupted innings, the method of target revision cannot and should not distinguish between whether Team 1's innings were terminated by being all out or by using up their (revised) allocation of overs.

3. When Team 2 have more resources than Team 1, why do you not simply scale up the target by the ratio of resources?

Cricket is an unpredictable game and how an innings starts may be no guide at all as to how it will continue. To scale up a target by the ratio of resources would be to assume that Team 1 would have batted as well, or as badly, in the overs they have lost as they had done in those that they actually faced. This could lead to some excessively high targets if Team 1 had achieved an early high rate of scoring and rain caused a drastic reduction in the overs for the match. We have preferred, therefore, to assume average performance for Team 1's additional loss of resource over Team 2.

4. But why should the target score sometimes go down if there is an interruption in the first innings and teams have the same number of overs?

In interruptions to the first innings the D/L method makes appropriate allowance for the comparative resources lost by the stoppage.

Consider the following situation. Suppose Team 1 started well in the style of the renowned Sri Lankan 1996 World Cup winning team but the wheels fell off and they were 150/9 in 30 of the 50 overs. On average Team 1 would be all out shortly, leaving Team 2 to score at the rate of around 3 per over for their full 50 overs. If rain interrupted play at this point and 19 overs were lost per side, then on the resumption Team 1 would have only one over to survive and their run rate would then be close to 5 per over. By all the 'old' methods, for 31 overs also, Team 2 would have to score around 150, around 5 per over, to win - in other words Team 1 would have been greatly advantaged by the rain interruption changing a required scoring rate of 3 per over to 5 per over for Team 2. By the D/L method this advantage to Team 1 would be neutralised so that the target for Team 2 would be well below 150 in this circumstance, and fairly so, which maintains the advantage Team 2 had earned before the stoppage. In other words, and quite logically, Team 2 have to get fewer runs than Team 1 scored to win in the same number of overs.

5. When Team 2 have the more resource, you increase the target by applying the excess resource to the quantity known as G50, which is the average score for a 50- over innings. Why do you not use a different value of G50 according to ground conditions on the day?

The key is simplicity. We accept that the value of G50 should, perhaps, be different for each country, or even for each ground, and there is no reason why any cricket authority may not choose the value it believes to be the most appropriate. In fact it would be possible for the two captains to agree a value of G50 before the start of each match, taking account of all relevant factors.

However, we not believe that something, which is only invoked if rain interferes with the game, should impose itself on every game in this way. In any case, it should be realised that the value of G50 usually has very little effect on the revised target. If 250 were used, for instance, instead of 235, it is unlikely that the target would be more than two or three runs different.

6. Why do we not use a higher value of G50 for games where the 15-over rule on fielding restrictions is applied?

The 15-over rule undoubtedly produces a higher scoring rate during those early overs, but, perhaps surprisingly, match data show there is little difference, if any, between the totals achieved with and without the rule. The benefits of higher scoring rate are probably being largely offset by the increased tendency to lose wickets.

We shall nevertheless keep the value of G50 under review, and if we see clear evidence that a different value should be used for any particular circumstances, we shall make the appropriate recommendation.

7. When Team 2's innings is interrupted, why do you not set a target which maintains the probability of achieving the target across the stoppage?

The problem with maintaining Team 2's probability of achieving their target across a stoppage is that it would mean that the target depended upon how many runs they had scored at the point of interruption. The more runs they had scored the more they would need, and the less they had scored the less they would need.

For instance, suppose that in three parallel matches, Team 1 score 250 in their 50 overs and Team 2's innings is interrupted after 20 overs with 10 overs lost in each case but with the scores at 60/2, 100/2 and 140/2. In all three cases the resources remaining were reduced from 68.2% to 54.0%, a loss of 14.2%, and so the target would be reduced by 14.2% of 250 to 215. If one set the revised target by scaling the runs still required by the resources remaining after and before the stoppage, which would maintain an equal probability of achieving the target, the targets would be different in the three cases, at 211, 219 and 228 respectively. It is surely unjust for a team to have to face a higher target because they had scored more runs.

The perceived problem with the way the revised target is set only arises when Team 2 are well ahead, or well behind, their par score. For instance, if they were 30 runs behind par at a stoppage and afterwards there was only time for a very few overs, they would still be 30 runs behind par and would have these few overs to make up the deficit, so their task may become virtually impossible. (If the match were washed out completely, they would have lost by 30 runs; nobody would dispute this.) It is Team 2's obligation to remain close to par to avoid losing if the match were terminated or their task being made more difficult if the innings were to be shortened.

8. How can Team 2 win by a number of runs?

When Team 2's innings is prematurely terminated by the weather the result is decided by comparing their score with their 'par score', this being the revised target, less one run, based on the loss of resource caused by the termination. Whether Team 2 have won or lost, the difference of their score from the par score is the best measure available of the margin of victory and so it has been decided that the result should be given in terms of this margin in all such cases.

Even when a game is not prematurely terminated it is still possible to describe a victory for Team 2 in terms of a margin of runs. When they hit the winning run their score will be ahead of par by a certain margin and there is a good case for expressing the result in terms of this margin of runs in all cases. For instance, if Team 2 score the winning run off the last ball available, to describe their victory in terms of the wickets they had in hand gives no indication of its narrowness.

9. During the last few years playing strategies have changed, eg sending in 'pinch- hitters' early on. Should not the numbers in the tables, which were produced a few years ago, have changed to reflect these changes?

Playing strategies are indeed changing and team selection strategies are changing also. And in addition rules and regulations change periodically and are liable to vary from competition to competition, for instance the rules for scoring off a no ball and the new laws on penalty runs for various infringements.

We are building up a detailed database of scores during innings and we are continually re-assessing the data. So after accumulating and analysing more than five years of data there is now sufficient evidence that the tables need updating. For competitions commencing on or after 1st Sept 2002 revised tables will be in operation."

10. Why don't you take away wickets as well as overs to balance up teams' resources?

Intuitively this sounds a very simple solution but, as with all other 'simple' solutions, it introduces more problems than it solves. One suggestion that has been made is that a wicket is removed for every (complete?) 5 overs lost (in 50-over per side matches)

So suppose for example: Team 1 have scored 250 in their 50 overs and then rain between the innings reduces the time for Team 2's innings to 25 overs. If you halve the runs to 125, with a target of 126 then this approach, which is now using the average-run-rate idea, would limit Team 2 to have only 5 wickets.

Sounds simple? But what if a match is shortened to an awkward number such as 41 overs per side before it starts? How many wickets are removed for a subsequent 7- over loss? And then another 6-over loss? Yes, it can be done but it isn't simple any more.

There is another problem in that wickets are not of equal value - the first 5 are more valuable than the last 5. So, in order to make it fair, which 5 wickets should be removed? What will the players so removed think of their compulsory exclusion from any more part in the game? And the spectators who may have come to see their favourite player bat and bowl? Both groups will be less than pleased.

Apart from these practical difficulties, which have already been recognised by cricketing authorities, there are many, many, anomalous situations that would arise.

The concept of this 'reduced wicket' rain-rule, and with most others before Duckworth/Lewis, is that it is assumed that interruptions only occur between the innings. But records show that very few rain-interrupted matches actually follow this pattern. Quite commonly, particularly in tropical climes, it is heavy rain late in the match that leads to its abandonment

For example suppose, as before, that Team 1 have scored 250 in 50 overs. Now suppose Team 2 have scored 199/1 in 40 overs and the match has to be abandoned? Who is the winner?

Using cricketing sense, Team 2 are well on top in the match and would be expected to go on to victory in the vast majority of such situations. Surely the rain-rule ought to reflect this superiority and award the match to Team 2? But their average run rate is only 4.98 compared to 5.0 by Team 1 and so Team 2 unfairly are declared the losers by this reduced wicket rule no matter that they have lost only one wicket.

Another scenario not satisfactorily addressed by the 'reduced-wicket' rule is the interruption to Team 1's innings. If Team 1 are 100/0 in 25 overs - well on the way to a 250-260 total - and then rain interrupts play so that there is only time for a 25 over innings from Team 2. The target would be 101 in 25 overs instead of around 125 (as above) if Team 1's innings had gone to completion. This is an easy target even with a reduction to 5 wickets and so doesn't address the disadvantage that Team 1 have suffered from the unexpected termination of their innings.

These are just two scenarios which illustrate potential problems and inequities that this reduced-wicket rule could create.

Proponents of this 'reduced wicket' rule argue that teams should be aware that average run-rate and wickets lost will be used for rain interruptions and should adapt their batting strategy accordingly. In the two examples the teams should bat, if they are aiming to achieve 250 or to beat it, so that they are up to 125/5 after 25 overs, 150/6 after 30 overs and 200/8 by the end of the 40th over etc by sustaining the average run rate of 5 per over throughout the innings. In reality most captains' strategy is to preserve some wickets in hand and to gradually increase the scoring rate in the later part of the innings. In other words the 'reduced wicket' rain-rule would be dictating batting strategy. We think it desirable that the rain-rule should fit within the existing character of the game and not try to change its nature.

And now a couple of questions which could conceivably arise. The answers are the same for both so they will be given after Q12.

11. Suppose we are playing a 50-overs-per-side game where only 10 overs per side are needed for the match to count. Team 1 send in pinch hitters and get off to a wonderful start making 100 for no wicket after 10 overs. There is then a prolonged stoppage and when play can resume Team 1's innings is closed and there is only just time for Team 2 to face the minimum 10 overs. The D/L calculation gives Team 2's target as 155 in 10 overs. How can this virtually impossible target be justified?

12. Same playing regulations as in Q11. Team 1 make the excellent score of 350 in their 50 overs and Team 2 start their reply cautiously and reach 35/0 in 10overs. The heavens now open (or the floodlights fail) and further play is ruled impossible. Under the D/L system Team 2 are declared the winners by 2 runs. They were clearly already falling behind the run rate they needed even allowing for the fact that they had all their wickets intact, so how can this result be justified?

The above represent the two worst case scenarios for treatment by the D/L method. They could only give such extreme consequences with playing regulations that allow a minimum of 10 overs per side for the match to count, and Q11 would not arise if the alternative regulation discussed in answer to Q1 were adopted. But a similar, though less exaggerated, injustice could still arise even with a minimum of 25 overs per side being required.

The D/L method has been devised so that anyone can perform the calculations with nothing more than the single table of resource percentages and a pocket calculator. This has been regarded as an essential requirement for the method. To be totally dependent on a computer would mean that the method could not be used universally, it would be vulnerable to computer failure and it would be virtually impossible to explain how the targets were calculated.

The use of the simplifying single table of resource percentages means that actual performance must necessarily be assumed to be proportional to average performance. In 95% of cases this assumption is valid, but the assumption breaks down when an actual performance is far above the average, as is the case in the scenarios of Q11 and Q12. It would be possible to adapt the D/L method to operate in terms of actual runs rather than percentages of the run scoring resources, but this would mean either that a separate table of runs available would be required for every possible Team 1 50-over score or that all the calculations were buried within the computer. The judgement of cricket authorities so far is that the occasional unjust target as exemplified by the extreme cases in Q11 and 12 is a price worth paying for the relative simplicity which the method as currently formulated allows.

13. How can copies of the full tables be obtained?

The tables are available to all cricket authorities. The general public may currently only obtain these by purchasing the booklet 'Your Comprehensive Guide to the D/L method …' which is available from Acumen Books, tel: +44 (0) 1782 720753, or see website: Acumen Books.

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