Are the regression model assumptions met?
Estimation of regression models is an iterative process. Once regression parameters have been estimated, functional forms have been specified, and indicator variables and interaction terms have been added to the model, it is wise to check the original assumptions, or requirements, of the regression equation. Not checking assumptions of the regression is poor practice, and may result in dissemination of a poor model. Thus, checking the assumptions is of utmost importance and should be the standard procedure in regression modeling.