The Average Run Rate (ARR) method was a mathematical formulation designed to calculate the target score for the team batting second in a limited overs cricket match interrupted by weather or other circumstances.
Often matches interrupted by weather would use reserve days, bowl outs, or be replayed on another date, but if logistics did not allow these, the ARR method would be used.
[1] If an interruption meant that the team batting second lost some of their overs, their target score was adjusted as follows.
[1] This formula could alternatively be written as: In other words, the target was reduced in proportion to the loss in overs.
There are four intrinsic flaws in the method: Two subsequent modifications were used: increasing the required run rate by 0.5% for each over lost, and calculating the target using the run rate after excluding maiden overs, with the revised target given by the next highest integer.