If we trained a hypothetical ZeroR classifier on this data, what would it predict? Since ZeroR ignores all of the features and simply predicts the target's mode, in plain language, its rule would state that all the mushrooms are edible. Obviously, this is not a very helpful classifier, because it would leave a mushroom gatherer sick or dead with nearly half of the mushroom samples bearing the possibility of being poisonous. Our rules will need to do much better than this in order to provide safe
advice that can be published. At the same time, we need simple rules that are easy to remember.