For a realistic evaluation of an arbitrary distribution, the fluctuation of the magnitudes within the flow field as well as its spatial distribution has to be considered. Therefore a good key value describing the quality of the distribution has to consider both. The coefficient of variation covers the effects of the fluctuations, but any spatial information is lost. Therefore, a complementary key value was developed to consider both attributes of the distribution - the fluctuations of the magnitudes, as well as its spatial distribution. The new method is successfully applied to vapour gas distributions within a distillation column with a large diameter.