A Nonsymmetric Responding Logistic Model for Forecasting Technological Substitution
This article presents a simple model of technological substitution termed as nonsymmetric responding logistic (NSRL). Based on the theory that substitution is an imitation process, the model can accommodate different patterns of technological substitution by allowing the imitation effect to vary over time systematically. It allows the S-curve to be symmetrical as well as nonsymmetrical, with the point of inflection responding to the substitution process. Data from four medical innovations are analyzed to illustrate the generality of the model.