Hébert-Johnson, Ú., Kim, M. P., Reingold, O. and Rothblum, G. N. (2018). Multicalibration: Calibration for the (computationally-identifiable) masses. In Proceedings of the 35th International Conference on Machine Learning (ICML 2018). ARXIV-1711.08513
Key takeaways
Read in full (NOTE-879). A predictor is α-multicalibrated on a collection C of subpopulations if, within every set S in C, the individuals given (roughly) the same prediction v have true probabilities averaging within α of v, except on an α-fraction of S. For any C whose sets have size at least γN, a simple iterative patching algorithm reaches multicalibration from O(log|C|/α^{11/2}γ^{3/2}) samples in time linear in |C|, and the result is a circuit only O(s/α⁴γ) in size when the sets of C are computed by size-s circuits. Learning it is equivalent, up to polynomial factors, to weak agnostic learning of C, so it is hard for rich C under cryptographic assumptions. Calibrating any predictor h on its own level sets as well as on C costs at most 6α in squared error. All guarantees are relative to the benchmark p*, which is itself defined relative to the features available, and they hold only for large sets; the paper offers no uniqueness for the predictor and does not state a theorem in indistinguishability form.
Why this is here
The owner asked whether material downstream of computational indistinguishability, or the signal detection literature, could help with CLAIM-302 and the bounded-observer questions. Read for QUESTION-103. Calibration relative to the subsets a class of computations can pick out is the individuation-by-sufficiency of CLAIM-152 with the observer’s resources made explicit. Machine-learning theory, with the anthology flag; filed here for that question.
The reading (NOTE-879) narrows this. The paper defines no distinguisher; its tests are first-moment checks on sets in the class intersected with level sets. The framing of adequacy as indistinguishability to a class is Dwork et al. 2021 (LIT-1068). Even with outcome, features and class fixed, the adequate predictor is not unique, and finding one can be hard where representing one is cheap.