The models are inductive, beginning with the development of curriculum materials and leading to generalization. Furthermore, the models are nonlinear. A nonlinear approach permits curriculum planners to enter a model at various points, skip components in the model, reverse the order, and attend to two or more components of the model simultaneously. Moreover, the three models are descriptive. A descriptive model, referred to as naturalistic by some scholars, include three major elements: platform, deliberation, and design (Walker, (1971). By platform is meant the beliefs or principles that guide the curriculum developers. Platform principles lead to deliberation, the process of making decisions from among alternatives. Deliberation results ultimately in a curriculum design.
(MAE). To investigate the sensitivity ofmodel performance to the number of
explanatory variables, the secondary variables were added to the models one at a time
until the best performance was reached.