A description of the curve-fitting process for the cost analyst. The study is characterized by intuitive discussions with illustrations of computational procedures, and treats the more complex relationships of cost analysis by an approach that integrates analytic geometry with curve-fitting methods. In order to develop an equation to describe a particular relationship, the approach combines the properties of specific functional forms--the straight line, the exponential, the power function, and the parabola--with the values of equation constants. Examples of curves fit to two-variable and multi-variable relationships are shown. Both linear and nonlinear cases are included. 147 pp. Bibliog.