Curve fitting
By John R. Hauser. By Claire Marton. Page 150. and to summarize the relationships among two or more variables. Encyclopedia of Research Design, Volume 1. Edited by Neil J. Salkind. Extrapolation refers to the use of a fitted curve beyond the range of the observed data. Community Analysis and Planning Techniques. By Richard E. Klosterman. This is subject to a degree of uncertaintyAn Introduction to Risk and Uncertainty in the Evaluation of Environmental Investments.