The two measures of dispersion which are used in statistical quality control are ρ, the expected value of the range of samples of a uniform sizen, and σ, the standard deviation of the population from which the samples are taken. Conversion of one into the other is facilitated by use of the quantity calledd2which is taken to be the ratio of ρ to σ. Tables ofd2versusnare reproduced in all texts on statistical quality control. These tables are predicated upon the parent population being normally distributed, an assumption which may be unjustified in many instances. To understand the consequences of this assumption of normality, a short table ofd2values based upon five distributions is presented. The five distributions are: normal, uniform, triangular, Erlang ν = 1 (negative exponential), and Erlang ν = 2. The sample size varies from two through 12, plus 15, 20, and 50. It was observed that for many values ofnthe normal distribution produced the largest value ofd2, while the negative exponential distribution produced the smallest value. Depending upon the intended use, and whether Type I or Type II error is of more concern, one may wish to used2values based upon other than the normal distribution. Some recommendations are made. A derivation of the formula for computing ρ as a function ofnwhich is dependent upon the parent population distribution is given in an appendix.