between two groups with respect to some features a solution is to attempt to define a boundary through the clouds of points to create a first zone which includes as much as practicable of the first group and as little as possible of the second group and a second zone which includes as much as practicable of the second group and as little as practicable of the first group the third zone is defined as an overlap region where no reliable classification can be made in principle a discriminant function weights the values of selected features for a new patient and adds these weighted values to specify a single point in the relevant multidimensional space this single point then would be in one of the three zones and the individual 39 s category in each of the di mi and pi would be classified accordingly the discriminant analysis is performed during the operation using z scores based on self norms i e comparison with the same patient pre operation and population norms i e patients of the same age and condition during similar operations using the same anesthetic after the di mi and pi are computed these computations may be used to automatically administer the various anesthetics to the patient.