Why were the discontinue rules shortened from the WAIS–III UK?
The shortened discontinue rules reduced the overall testing time. Standardisation discontinue rules were set generously to enable the examinee to attempt all passable items, yet limit the number of items presented. Final adjustments to the discontinue rule for each subtest were made based on empirical studies of the standardisation data. The percentile ranks of examinees within an age group were compared before and after application of the reduced discontinue rule. The discontinue rule was set at the lowest number of consecutive scores of 0 that resulted in a rank-order correlation of .98 or higher. For example, the Similarities discontinue rule was five consecutive scores of 0 for standardisation and was reduced to three consecutive scores of 0 for the final version of the scale.
