C. R. Tiedeman M. C. Hill 2002 This paper investigates four issues related to weighting observations in the context of groundwater models calibrated with nonlinear regression: (a) terminology, (b) determining values for the weighting, (c) measurement and model errors, and (4) the effect weighting can have on the accuracy of calibrated models and measures of uncertainty. It is shown that the confusing aspects of weighting can be managed, and are not a practical barrier to using regression methods. application/pdf en Weighting observations in the context of calibrating groundwater models article