Every model has a set of parameters that represents the materials, organisms, environment, etc.
The proper selection of parameters spells the difference between a model and a model that has predictive power. Uncertainties in parameter estimates translate into uncertainties in the states and conditions of direct importance to a manager . For many, the term characterization embraces a broader scope than the term parameter estimation . It includes the descriptive assessment of soils and rocks, and the estimation of the distribution of contaminants or hydraulic heads from sparse data, as well as estimating the spatially varying value of material properties such as hydraulic conductivity. For some, characterization is the process of physically collecting data that support such inferences.