Comparison of VJD method with the Duckworth-Lewis method

Source:Wikipedia

Both the Duckworth-Lewis method and the Jayadevan System use a statistical method to determine what proportion of a team's runs it is expected to have scored, based upon the number of overs faced and the number of wickets lost (traditionally referred to as the resources available to a team). However, there are two primary differences between the two methods:

• The mathematical relationship used in the Duckworth Lewis system assumes that a team's scoring rate accelerates throughout the team's innings – slowly at first, but more rapidly during the final ten to fifteen overs (the "slog overs"). Jayadevan's relationship is more empirical than Duckworth-Lewis', and assumes that the scoring rate is faster during the first fifteen to twenty overs during fielding restrictions, decelerates during the middle overs when most teams try to consolidate their innings, and then accelerates again for the slog overs. In this way, Jayadevan tries to improve upon Duckworth-Lewis' notion of the "typical innings".
• Secondly, Duckworth-Lewis is based upon a single set of curves which is used to make all adjustments to the scores. The Jayadevan method has two different curves: the "normal curves", which are used to adjust runs already scored by the batting team; and the "target curve", which is used to adjust the runs that the batting team is yet to score. Jayadevan's justification for this is that prior to a rain interruption, a team will base its batting tactics on the assumption that it has its full quota of overs available; but, following an interruption, a team can change its batting tactics to suit the new number of overs – so, if the tactics are inherently different, the curves used to calculate the run targets should also be different.

Under Jayadevan's method, the "normal" curve takes into account both the percentage of overs played and the percentage of wickets lost. The "target" curve considers only the percentage of overs played; i.e. no adjustment is made according to the number of wickets lost.