I am doing classification of this UCI Dataset in Matlab. I represented dataset as matrix (instances x dimensions) and 2nd matrix as (instances x label [instances x 1]).
With Naive Bayess I get accuracy of multiclass classification 0.65. But when I use dataset transformed with PCA I get accuracy only 0.15 even if I use all dimensions. I guess I am doing something wrong. This is my matlab code:
%x_tr, y_tr =training set, labels of training set %x_tst,y_tst=testing set , labels of testing set model = fitNaiveBayes(x_tr,y_tr); Y=predict(model,x_tst); acc=accuracyMC(Y); %0.65 %PCA usage [COEFF,SCORE] = princomp(x_tr); model_pca = fitNaiveBayes(SCORE,y_tr); [COEFF,SCORE] = princomp(x_tst); Y=predict(model_pca,SCORE); acc_pca=accuracyMC(Y); %0.15
I also tried normalize it with z-score.