Numerical Diagnosis Using ``Statrules´´

In some cases disease causes widespread changes in a number of physical and chemical indexes, without any one index being grossly altered. The difficulty inherent in evaluating numerous small changes may obscure the diagnosis, even though it is conclusive. We show that subtle patterns of change may be recognized using marked cards. These consist of a ``patient data card´´ on which is typed a number of scales, each representing one of the measurements, and a ``statrule´´ card which contains the statistics for these measurements for the diseases of concern. These cards implement procedures often used in studies of numerical diagnosis made with digital computers. The statistical basis of statrules is discussed in the first part of the paper using primarily a geometric point of view. The second part of the paper shows how to use and construct statrules.