A plotting rule for extreme probability paper

A primary purpose in plotting a set of ordered observations on probability paper is to simplify the inspection of their distribution. With this limited objective a plotting rule for the ith of n ordered observations from a double exponential distribution is obtained as i = (i - 0.44)/(n + 0.12), where n is the number of observations, i is the order of the observation from the smallest, and i is the estimate of the cumulative frequency of the ith term.