Hello, I use the function qda (package MASS) to obtain a qda object like below. x.qda = qda(x, group) the group is a factor of two levels and use this object to do the prediction below. y.pred = predict(x.qda, y) after that, I set different prediction priors like below, but the results of prediction are totally the same as above using prior of training set (use all.equal to compare). y.pred1 = predict(x.qda,y, prior = c(1, 0)) y.pred2 = predict(x.qda,y, prior = c(0.5, 0.5)) y.pred3 = predict(x.qda,y, prior = c(0, 1)) y.pred4 = predict(x.qda,y, prior = c(0, 0)) the prediction prior of the last one should be wrong, but I still got the same result. And I tested the example of the function predict.qda by setting a prediction prior. predict(z, test, prior = c(0.1, 0.1, 0.8)) this result is exact the same as "predict(z, test)" which use training prior "c(0.3333333, 0.3333333, 0.3333333)" If the prediction prior for qda does not work? The version of R I use is 2.1.1, and this argument for lda works. Thank you, Shengzhe
Hello, I use the function qda (package MASS) to obtain a qda object like below. x.qda = qda(x, group) the group is a factor of two levels and use this object to do the prediction below. y.pred = predict(x.qda, y) after that, I set different prediction priors like below, but the results of prediction are totally the same as above using prior of training set (use all.equal to compare). y.pred1 = predict(x.qda,y, prior = c(1, 0)) y.pred2 = predict(x.qda,y, prior = c(0.5, 0.5)) y.pred3 = predict(x.qda,y, prior = c(0, 1)) y.pred4 = predict(x.qda,y, prior = c(0, 0)) the prediction prior of the last one should be wrong, but I still got the same result. And I tested the example of the function predict.qda by setting a prediction prior. predict(z, test, prior = c(0.1, 0.1, 0.8)) this result is exact the same as "predict(z, test)" which use training prior "c(0.3333333, 0.3333333, 0.3333333)" If the prediction prior for qda does not work? The version of R I use is 2.1.1, and this argument for lda works. Thank you, Shengzhe