i konw the lda and qda in MASS can do discriminant analysis.and lda complete the Fisher's method.and qda is the Quadratic discriminant analysis. 1,my first question is if qda do the Mahalanobis's method? 2,as some textbook say,when using fisher's method,"we proceed by assuming that the within-group covariance structure for our data is the same across groups",so we need test for equailty of covariance matrices. my question is :when i using lda,should i test equailty of covariance matrices first? and can R do these? thank you !
i have find the answer to this question. sorry for my overlook the information about it in internet.> 2,as some textbook say,when using fisher's method,"we proceed by assuming that the within-group covariance structure for our data is the same across groups",so we need test for equailty of covariance matrices. my question is :when i using lda,should i test equailty of covariance matrices first? and can R do these?the box's m test is the way for this purpose,but the test does not have good property.so it is not worthwhile for us the do the test.