Question: Explain how each of the following tests can be considered as a test for the coefficients of some extra variables added to the original equation.
(a) Test for serial correlation.
(b) Test for omitted variables.
(c) Test for errors in variables.
(d) Test for exogeneity.
(e) J-test.
(f) PSW differencing test
In each case explain how you would interpret the results of the test and the actions you would take.