Sampling of discrete materials—a new introduction to the theory of sampling: I. Qualitative approach

The purpose of a theory of sampling is to answer two questions: How should one select a sample?—How much material should be selected? Parts I (qualitative approach), II and III (quantitative approach) of this series propose answers to these two fundamental questions. These answers are not entirely new (answers have been formulated since 1950), but a scientific theory is a living structure that has to be kept up to date. At a course given in Brasilia in 1998, pointed questions were raised which suggested that the introduction to the qualitative approach had to be clarified. Part I represents the most updated introduction to theory of sampling (TOS). More than 200 scientific papers, books, lectures and courses on sampling theory—and practice—have been published or offered to the public by the author over a period of 50 years. A brief, chronological account of the development history of TOS is presented for the first time in part IV—with a comprehensive literature survey as part V.