chapter  10
32 Pages

More Complex Relationships

ByRoger Mead, Robert N. Curnow, Anne M. Hasted

This chapter is concerned with more complex relationships estimated in different environments and with examining the possible dependence of y on several x variables. The y variable is called the dependent variable and the x variables are called independent variables. The chapter considers the situation where the relationship between y and x is not linear, that is, cannot be represented by a straight line. Multiple regression is a very powerful tool for investigating relationships. The chapter describes the principles and illustrates the use of multiple regression. The calculations for fitting multiple regression will inevitably involve the use of a computer package. More complex regression techniques, known as weighted regression, can be used if the transformation to linearity has not also achieved a constant variance. Even the computer can experience computational difficulties in multiple regression fitting and the users of multiple regression programs should beware of the computational problems that may arise.