The confidence we have in the prediction capabilities of a given method has something to do with probabilistic forecasting; this however, may depend on factors difficult to quantify, such as deciding about the probability we consider good enough to take a decision. Ideally, a DFA should be judged on its prediction uncertainty, like any measurement method, but this requires the correction of systematic errors, which goes beyond the realm of the DFA itself. (3.3.13) Savin : Could it be that the importance of accuracy is overemphasized? Let us take as an example the intensive atomization energies (i.e., per atom) as obtained with the B3LYP functional on a widely used benchmark data set. Let us now consider what the measures mentioned in contribution (3.3.12) provide. The often quoted "chemical accuracy" of 1 kcal/mol corresponds to the mean absolute error of the B3LYP functional However, this accuracy is reached by only about half of the systems in the data set.