dr_whom

Trudgill (1972), "Sex, covert prestige and linguistic change in the urban British English of Norwich":

There are two possible pronunciations of this variable: [iŋ], which also occurs in the prestige accent, RP, and [ən ~ n]. The former is labelled (ng)-1 and the latter (ng)-2. Index scores were developed for this variable by initially awarding 1 for each instance of (ng)-1 and 2 for each instance of (ng)-2. These scores were then summed and divided by the total number of instances, to give the mean score. Indices were finally calculated by subtracting 1 from the mean score and multiplying the result by 100.

…Nominee for the most convoluted way of calculating a percentage.