Misspecification Tests in Econometrics: The Lagrange Multiplier Principle and Other ApproachesBy bringing together results from the growing literature in econometrics on misspecification testing, this study provides theoretical analyses and convenient methods for the implementation of tests in applied work. Although the main emphasis is on the Lagrange multiplier principle, several other approaches are discussed and the relationships among different methods are examined. The author reviews general checks of model adequacy that do not involve