I have a tagged csv file with 5 calsses. I accidentally trained am XGBOOST model with this input but forgot to change the num_classes to 5, but instead it was still 2.
The model I received seems to be a very good one, I have tested it on several data sets. I tried to correct the error and set it to 5, that produced a much worse model.
Does anyone know what is the behavior of the training in such a case? Because I cant really explain why my model is working that good.
Edit: we are using Confusion Metrix to determine how good is the model:
y_pred = randomized_mse.predict(X_test)
we set num_class": , when in fact we have 5 classes in the data set