This is the perfect (and essential) supplement for all econometrics classes--from a rigorous first undergraduate course, to a first master"s, to a PhD course. - Explains what is going on in textbooks full of proofs and formulas; - Offers intuition, skepticism, insights, humor, and practical advice (dos and don"ts); - Contains new chapters that cover instrumental variables and computational considerations; - Includes additional information on GMM, nonparametrics, and an introduction to wavelets.