Regression and correlation are concepts that are associated with the relationships between two or more random variables. Both were discussed briefly in Chapter 9, correlation in Section 9.8 and regression in Section 9.10. In this chapter the coverage will be expanded and made more complete. The subject matter associated with regression and correlation is, however, far too extensive for complete coverage here. For more information, reference is made to such standard texts as Draper and Smith (1981).