Training and testing sets
		n Where does the test set come from? 1. Collect a large set of examples 2. Divide into training and testing data 3. Train on training data, assess on testing 4. Repeat 1-3 for different splits of the set. n Same distribution    “Learning … enable[s] the system to do the task or tasks drawn from the same population” – Herb Simon ¡ To think about: Why?