I am examining the mismatch between field of study during college and future employment, and how the mismatch may impact returns to education. I am using data from the National Survey of College Graduates. They have an indicator asking respondents why they are working in a field outside of their college major (i.e. pay, location, interests ect.) Would it be appropriate to generate a new variable that encompasses the different reasons why they are working outside of their field of study to indicate if the person is mismatched, and then interact this new variable with each major type?