TABLE OF CONTENTS Heterogeneous is an adjective defined in Merriam Webster's Collegiate Dictionary, Tenth Edition as " consisting of dissimilar ingredients or constituents." [ ] In essence, heterogeneous means "not all the same" or "not uniform throughout" or "different." Without a doubt, all the materials we sample are heterogeneous, whether they are solids, liquids, gases, or a combination. In other words, there is no such thing as a pure material, either natural or artificial. The presence of heterogeneity, the noun corresponding to the adjective heterogeneous, is why physical samples differ and why they generate variation. There are two types of material heterogeneity, and each gives rise to a sampling error: constitution heterogeneity [3] ( CH) and distribution heterogeneity ( DH). From Gy's perspective, "Heterogeneity is seen as the sole source of all sampling errors" (Gy, 1998,p. 24).
Admittedly, these words are a mouthful. But fortunately, they are very intuitive and descriptive. CH refers to the differences in the constitution, or makeup, of the material: how alike or different the individual particles or molecules are. DH refers to differences in how the material is distributed: how well mixed or segregated the material is due to density, particle size, or other factors. Each of these two types of heterogeneity gives rise to a sampling error. Together they determine how variable our samples can be and how easy or hard it is to get consistently representative samples. Because...
