Beyond Ranking: Are Decision Models Calibrated Relevance Scorers?
Shengyao Zhuang, Xueguang Ma, Matthias Petri, Jimmy Lin
原文摘要
Decision models such as Jev are a new kind of relevance scorer. Their typed score primitive takes a question, an ordered set of textual relevance levels and a state, and returns a probability for each level directly, rather than token likelihoods or generated labels. Jev's vendor promises that these probabilities are calibrated. This motivates revisiting 'Beyond Yes and No', which improved zero-shot pointwise LLM reranking using likelihood-derived scores over fine-grained relevance labels but left calibration against human assessors as future work. In this paper, we first reproduce its open-model FLAN-UL2 setting on eight BEIR collections, confirming its ranking trends, and then run Jev and two open-weight decision models with the same protocol. Jev and the 27B pplx-decider rerank ahead of FLAN-UL2 and three cross-encoders on average. We then compare Jev's native probabilities with the human assessors' labels and find them overconfident: of the DL21 pairs it scores above 0.9, only 66% are relevant. Since this is mostly an error of scale, a two-parameter calibration fitted on 2,257 DL19 pairs removes much of it and transfers to DL21. After calibration, Jev has a lower DL21 Brier score than FLAN-UL2 and the three cross-encoders, mainly because it separates relevant from non-relevant pairs better. Finally, with calibrated probabilities, choosing each query's cut-off by expected F1 needs no parameter of its own, beats a fixed top-10 cut and matches a cut-off threshold tuned on DL19.
cs.IR