On Tue, 1 Apr 2003, array chip wrote: > > I used the "lda" function in the MASS library of S-Plus (R) to do a > linear discriminant analysis, and got the linear coefficients, say b1 > and b2 for the 2 predictors x1 and x2. I have trouble to calculate the > discrimiant scores for each observation, I used 3 ways to try to repeat > the scores returned by the "predict" function in S-Plus: > > 1. b1*x1+b2*x2 > 2. b1*(x1-mean of x1)+b2*(x2-mean of x2) > 3. b1* standardized x1+b2*standardized x2 (standardize: mean 0 & variance 1) > > none of the above procedures can repeat the scores returned by the > "predict" function. However, method 2 & 3 can predict the classes > correctly if using 0 as cutoff, juts like using the "predict function".
You've sent this to R-help, but S-PLUS (sic) and R are different as is my lda() function in each. MASS is a book, and it contains the details, as does the code. > What should be the correct formula to compute the scores for each > observation? > > BTW, how to retrieve the linear coefficients from an lda object? I can't > retrieve it by using @coef, @coefficients, etc. Of course not: in R these are not S4 classes. You could read the help page to see what lda() actually computes. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
