The adjectives randomized and ordered distinguish these equations. Randomized implies that the order in which squared differences between the central value and measured values in the set are added does not impact the numerical value of the variance. In contrast, ordered implies that all measured values in the set are in the same sequence as they were in the sample space. If both terms are properly defined, the terms variance and variances of ordered set would be adequate.

Both equations apply to sets of measured values with equal weights such as test results for core samples of the same length and density, bulk samples of identical mass, or central values of ore sections in equidistant boreholes. Core samples of variable length and density, bulk samples of variable mass, and central values of ore sections in boreholes at variable distances, require that proper weighting factors be applied to all terms in the above equations. The equations required for this calculation can be found in Sampling in Mineral Processing (see Reviewed papers).

After geostatistics was hailed as a new science, the variance of a randomized set metamorphosed into "sill value", and the analytical variance was transformed into "nugget effect". While it is true that geostatistical neologisms reveal paucity, the penchant for neologisms and the use of the "krige" eponym as an adjective and a verb explains why so many geospeak terms are at variance with those defined by ISO Technical Committee 69-Applications of Statistical Methods.