Elimination of Source A and B Errors in p-Median Location Problems

The p-median problem is a powerful tool in analyzing facility location options when the goal of the location scheme is to minimize the average distance that demand must traverse to reach its nearest facility. It may be used to determine the number of facilities to site, as well as the actual facility locations. Demand data are frequently aggregated in p-median location problems to reduce the computational complexity of the problem. Demand data aggregation, however, results in the loss of locational information. This loss may lead to suboptimal facility location configurations (optimality errors) and inaccurate measures of the resulting travel distances (cost errors). Hillsman and Rhoda (1978) have identified three error components: Source A, B, and C errors, which may result from demand data aggregation. In this article, a method to measure weighted travel distances in p-median problems which eliminates Source A and B errors is proposed. Test problem results indicate that the proposed measurement scheme yields solutions with lower optimality and cost errors than does the traditional distance measurement scheme.     

Recursive Algorithm for Determination of Proximal (Thiessen) Polygons in Any Metric Space

A new and recursive algorithm for determining proximal polygons is based on quadtree concepts. The algorithm can use any distance metric, and produces a quadtree of the image of the proximal polygons. This can be converted to vector form, or be incorporated directly into a quadtree-based geographic information system, in order to solve a number of closest-point problems. The algorithm can also produce the Delaunay triangulation, which is the dual of the proximal polygons. Empirically, the running time of the algorithm is proportional to the number of centers raised to the 1.6 power.     

Reviews of books

Historical Archaeology -     

Illicit Drug Production and Supply-side Drugs Policy in Asia and South America

This paper examines the feasibility of current policies of supply limitation as an instrument for the control of dangerous drugs (principally South American cocaine and Asian heroin). The structure of production and distribution is examined, and revenue estimates are made. A range of supply-side policy options are evaluated by means of a simple game-theory approach. In all cases, it is concluded that supply-side policies are likely to prove ineffectual as a means of drug control.     

TECHNICAL CHANGE AND PROFITS IN CANADIAN MANUFACTURING: A REGIONAL ANALYSIS

Manufacturing profitability and growth declined sharply in Canada between 1955 and 1984. The spatial extent of this decline has not previously been documented. This article examines manufacturing performance in six regions of Canada. The analysis reveals significant interregional performance differences that appear to be increasing. Two different types of inter-firm competition are identified in the article: competition in production and competition in the market. Empirical investigation reveals that changes in production conditions had a greater impact on regional profitability in five of the six regions studied. In the remaining region, poor market performance was the primary cause of the reduction in profits after 1955.
Au Canada la rentabilité et la croissance industrielle ont profondément diminué entre les années 1955 et 1984. L'ampleur spatiale de cette baisse n'a jamais été docu-mentée. Cette étude examine le comportement et les performances de fabrication dans six régions canadien-nes. De considérables différences inter-régionales, qui semblent toujours s'accentuer sont mises en évidence. Dans cette recherche, deux genres de concurrence entre les societes son identifiés: la concurrence dans la production, et la concurrence dans le marché. L'analyse empi-rique montre que certains changements dans les conditions de production ont eu un effet considérable sur la rentabilité régionale pour cinq des six régions en question. En ce qui concerne la dernière région, la baisse des profits a partir de 1955 est dûe essentiellement à la mauvaise performance du marché.