Modern econometrics stresses the diagnostic testing of estimated models as an important part of the model-building process. In a survey article published in this journal (Pagan and Vella 1989), methods for testing the validity of the assumptions underlying the censored regression of the Tobit...

A non-technical introduction to the question of modeling with time-varying parameters, using the beta coefficient from Financial Economics as the main example. After a brief introduction to this coefficient for those not versed in finance, the book presents a number of rather well known tests...