ABSTRACT
One of the first steps in modeling is to make simplifying assumptions, and one of the simplest assumptions is that one variable is simply a constant multiple of the other. This type of relationship is called proportionality. One famous proportionality relationship is Hooke’s Law which relates the force applied to a spring to the distance it is stretched or compressed. One important observation about a proportionality relationship is that if one of the variables increases, so does the other, and if one variable decreases, so does the other. This chapter shows how to use proportionality and geometric similarity as simplifying assumptions in the modeling process and how to use data to find constants of proportionality. In simpler terms, two objects are geometrically similar if one is a scaled up or down version of the other. The chapter also uses the coefficient of determination to assess how well a model fits a set of data.
