Since the evaluation of the homogeneity of a distribution can be subdivided into two parts (magnitude and spatial distribution), a good key value describing the quality of the distribution has to consider both. The value of the coefficient of variation (Coy) covers the effects of the fluctuation's magnitude, but any spatial information is lost. Therefore, a complementary key value (Coefficient of Distribution CoD) was developed to consider both, magnitude and spatial distribution together. The new method is successfully applied to evaluate the vapour velocity distribution at the entrance to the packed bed above the vapour feed of an industrial distillation column with a large diameter. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.