GDA deals with nonlinear discriminant analysis using kernel function operator. Logistic regression is an alternative to Fisher's 1936 method, linear discriminant analysis. An eigenvalue in discriminant analysis is the characteristic root of each function. Logistic regression does not have as many assumptions and restrictions as discriminant analysis. The test has convergent validity but not discriminant validity. This leads to the framework of regularized discriminant analysis or shrinkage discriminant analysis. The discriminant of a linear polynomial (degree 1) is rarely considered. Convergent evidence is best interpreted relative to discriminant evidence. The following table shows some orders of small discriminant of quadratic fields. There is no common convention for the discriminant of a constant polynomial (degree 0). The Hessian determinant of is formula 81 times its discriminant. "The use of multiple measurements in taxonomic problems" as an example of linear discriminant analysis. Construct validity and discriminant validity has also been established. The determinant of the Hessian at is called, in some contexts, a discriminant. The assumptions of discriminant analysis are the same as those for MANOVA.