This brief describes exploratory work to develop a simulation model to predict the potential implications of changes that may be coming in policies and practices related to school meals and school food environments.

This paper proves that it is wrong to require that regressing a model's outputs on the observed real outcomes gives a 45 degrees line through the origin (unit slope, zero intercept).Therefore this paper proposes an alternative requirement: the responses of the model and the real system should...

Simulation models may have many parameters and input variables (together called factors), while only a few factors are really important (parsimony principle). For such models this paper presents an effective and efficient screening technique to identify and estimate those important factors. The...

Rigorous statistical validation requires that the responses of the model and the real system have the same expected values. However, the modeled and actual responses are not comparable if they are obtained under different scenarios (environmental conditions). Moreover, data on the real system...