Introductory Econometrics: A Modern Approach 6th Edition by Jeffrey M Wooldridge

Exercise 5

In equation (4.42) of Chapter 4, compute the LM statistic for testing whether motheduc and fatheduc are jointly significant. In obtaining the residuals for the restricted model, be sure that the restricted model is estimated using only those observations for which all variables in the unrestricted model are available (see Example 4.9).