Uncertainty and Variability Analysis

Abstract

Statistical methods are an inseparable component of all modeling studies. Most environmental processes we have covered in this book do not lend themselves to a deterministic mode of analysis because of the inherent uncertainties involved in the parameter values that describe the physical system analyzed. These uncertainties may arise from the randomness of the natural processes, a lack of data to represent the parameters of the model or a lack of understanding of the processes that are used in the model that is built. Statistical methods may be used to account for these uncertainties. In most cases, for the completeness of the study, the deterministic analysis provided should always include a probability analysis of the occurrence or the likelihood of occurrence of the results presented. Thus, given the complex or simple nature of the models and the modeling tools developed in this book, it is important to provide an introduction to the statistical methods that are used in uncertainty and variability analysis that may be used in these models. The purpose of this chapter is to introduce the reader to these concepts.