systems Abstract. The technology for building knowledge-based systems by inductive inference from examples has been demonstrated successfully in several practical applications. This paper summarizes an approach to synthesizing decision trees that has been used in a variety of systems, and it describes one such system, ID3, in detail. Results from recent studies show ways in which the methodology can be modified to deal with information that is noisy and/or incomplete. A reported shortcoming of the basic algorithm is discussed and two means of overcoming it are compared. The paper concludes with illustrations of current research directions. 1.

CH-1401 Yverdon-les-Bains, Switzerland This article reviews a number of statistical tests for comparing proportions. These statistical tests are presented in a comprehensive way, so that OR practitioners can easily understand them and correctly use them. Atestfor2 × 2 contingency tables is developed and shown to be more powerful than other classical tests of the literature such as Fisher’s exact test. Tables with critical values for small samples are provided, so that the test can be conducted without any computations.