 As a result, the notion of \(\lambda\)-mediation (encountered in  §4.1)  is replaced by the notion of \(\omega\)-mediation, in which the ontic process \(\omega\) completely specifies the properties of the environment that mediate correlations between regions, and screens off outcomes produced by local controllables from the rest of the environment. Shrapnel and Costa (2018: 9) define the notion of “instrument noncontextuality” as a law of parsimony (along the lines of Spekkens’ own definition of noncontextuality): “Operationally indistinguishable pairs of outcomes and local controllables should remain indistinguishable at the ontological level”. They then show that no instrument noncontextual model can reproduce the quantum statistical predictions.