The core methods in today's econometric toolkit are linear regression forstatistical control, instrumental variables methods for the analysis ofnatural experiments, and differences-in-differences methods that exploitpolicy changes. In the modern experimentalist paradigm, these techniquesaddress clear causal questions such as: Do smaller classes increase learning?Should wife batterers be arrested? How much does education raise wages?_Mostly Harmless Econometrics_ shows how the basic tools of appliedeconometrics allow the data to speak.In addition to econometric essentials, _Mostly Harmless Econometrics_ coversimportant new extensions--regression-discontinuity designs and quantileregression--as well as how to get standard errors right. Joshua Angrist and Jörn-Steffen Pischke explain why fancier econometric techniques are typicallyunnecessary and even dangerous. The applied econometric methods emphasized inthis book are easy to use and relevant for many areas of contemporary socialscience. * An irreverent review of econometric essentials * A focus on tools that applied researchers use most * Chapters on regression-discontinuity designs, quantile regression, andstandard errors * Many empirical examples * A clear and concise resource with wide applications