Heterogeneity of a Zero-Dimensional Lot: Constitution and Distribution Heterogeneities

The two types of heterogeneity investigated in this chapter are those encountered in a zero-dimensional lot. By definition, the various units of a zero-dimensional lot form a population in which their order is non-existent or at least considered irrelevant. The notion of heterogeneity is somewhat confusing in the minds of many people, and there are several reasons for this: There are several types of heterogeneity: The heterogeneity consisting of a difference between the composition of the different units of a lot, such as between fragments, if we are talking about a lot of particulate material as an example. This heterogeneity is defined as the Constitution Heterogeneity CH . There is another form of heterogeneity which is defined as the Distribution Heterogeneity DH , consisting of a difference between the spatial distribution of the different units within the lot, such as different fragments of a lot of particulate material. Their physical characteristics explain somewhat the reasons for their position. Everyone knows that this kind of spatial heterogeneity is generated because fragments have different shapes, densities, and weight, to mention only a few of their intrinsic properties. Most authors speaking of heterogeneity never specify the type of heterogeneity they refer to, thus creating confusion for those trying hard to understand the complex concept of heterogeneity. Our objective in this chapter is to clearly define and study these two important forms of heterogeneity associated with a given constituent of interest, and to link them to one another.