Which approach to choose?
Determine a model that fits observed data as closely as possible

This is an essential question when it comes to calibration. When we look at the reality of calibration conditions and the conditions of use of a particular approach, only the so-called GGMR technique fits the context. A few years ago, the Collège français de Métrologie ( CFM ) brought together a group of experts to draw up a guide to modeling. In addition to the guide, the CFM distributes an Excel application, M-CARE, free of charge on its website, which can be used to implement all least squares techniques, and in particular the GGMR technique. The application can also be used to calculate the variance/covariance matrix on available data.