This book was originally published as a doctoral thesis and was de­ fended by the author at the Tilburg School of Economics in 1969. It has the characteristics of a work on industrial econometrics. On the one hand relevant economical, statistical and mathematical theory is treated and on the other a model for a very actual situation has been created and utilised to solve a practical problem. The selection from current reference material always has a personal tinge of course, and other theoreticians will find some of the author's departures from the theme a little unnecessary. However, if the theory propounded in this book is tested for its relevance in solving practical problems, the selection may be regarded as a success. Thanks to the way in which the case is developed the book is of great practical use. So often in writings on operations research theory is applied to so-called practical examples, which in fact can only be des­ cribed as five finger exercises. It is clear from the early chapters that the author has struggled with this problem but that he has found a solution. And in his concluding remarks he indicates briefly how this case can be incbrporated in a context which goes beyond short-term optimisation. In the description of the preparatory and implementation phases the author shows how a clash between practical implementation and theoretical application can successfully be avoided in this preparatory work.