 Our discussion of improper linear models  (section 2.3)  mentioned a model that often comes surprisingly close to approximating a proper linear model, and our discussion of the bias-variance decomposition  (section 4.2)  referred to conjectures about how cognitive systems might manage to make accurate predictions with very little data . In this section we review examples of models which deviate from the normative standards of global rationality yet yield markedly improved outcomes—sometimes even yielding results which are impossible under the conditions of global rationality. Thus, in this section we will survey examples from the statistics of small samples and game theory which point to demonstrable advantages to deviating from global rationality.