In the book an attempt has been made to develop some new diagnostic
tests for statistical model building in the context of linear regression
models. Diagnostics of outliers has been described and a test for
identifying outliers by using predicted residuals has been proposed in
the present study. Besides outliers, a measure of influence for
diagnostics has been developed in the study. Some new modified R2 and
criteria for model selection have been developed along with modified
mean square prediction error criteria; and modified information criteria
for model selection. A test for exogeneity in model specification by
using augmented regression model; and a test for stability of regression
parameters in model specification have been proposed under diagnostic
tests. A new test for misspecification of the linear regression model
has been derived along with a modified Rainbow Test by using Internally
studentized residuals. The problem of misspecification of non-nested
linear regression models, has been discussed together with a diagnostic
test for functional form between loglinear and linear regression models.