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P E File

Publications and source records attributed to P E File.

5 recordsLinked to original sources
PubMed1994

Evaluation of the use of induction in the development of a medical expert system.

In an earlier study, two medical expert systems for diagnosing thyroid disorders, developed by the application of induction on a sample of previously diagnosed cases and on expert-generated rules, diagnosed a set of test cases better than an expert system developed by the more traditional method of collaboration between a knowledge engineer and an expert. In this paper, an alternative measure of the accuracy of diagnosis of each system is used to evaluate the systems. Diagnoses for every distinct case represented by a combination of indicating factors are compared with diagnoses that the expert made. The induced systems provide diagnoses for many more distinct cases, but a much higher proportion of these diagnoses are incorrect. It is argued that generalizing to unseen cases is an inappropriate use of induction algorithms. The systematic development of a decision table is a more appropriate method for devising a medical expert system.

Decision Making, Computer-Assisted↗
PubMed1980

Comparing two objects for size after a comparison of one of the objects with other objects.

When shown the names of two objects, subjects determine which object is larger more slowly as the difference in the sizes of the objects decreases. This might result from variations in the time taken to access sufficient information to perform the task; information which crudely specifies size is accessed first and can be used when the sizes differ greatly; information which specifies size on a more finely graded scale must be accessed when they do not. This hypothesis was tested. Subjects shown the names of three objects, determined which object was intermediate in size. Immediately thereafter the name of another object was shown, the task then being to decide whether the object previously judged intermediate was larger than this object. In this second task reaction times increased with decreasing differences in size between the two objects; this increase was smaller, however, when the sizes of the objects in the first task were similar. The results were predicted from the assumption that when the specification of an object's size in terms of fine discrimination is accessed for comparison in the first task it remains available for use in the second task; thus the time normally required for accessing that information in the second task is reduced. Some implications of the results are discussed.

Cognition↗