The file P4_2.XLS contains information on 66 movie stars. In particular, the data set contains the name of each actor and the following four variables: gender, domestic gross (average domestic gross of the star’s last few movies, in millions of dollars), foreign gross (average foreign gross of the star’s last few movies, in millions of dollars), and salary (current amount the star asks for a movie, in millions of dollars). Are all of these data usable? Explain why or why not.