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What Fixed-Rollout pass@k Evaluations Can Identify

arxiv.org/abs/2609.09245

Updated 51 min ago · first seen 11 Sept 2026

paper_01M294GKY6VPGCD6C7RJX1VNM4

Published
11 Sept 2026
T1 · 51 min ago
arXiv
2609.09245
T1 · 51 min ago
Category
stat.ML
T1 · 51 min ago

Abstract

Repeated-sampling evaluations increasingly extrapolate pass@k far beyond the number n of samples collected per problem. We show that, in the pooled/random-task conditional-Binomial model, fixed-n success counts identify only the n free moments of the latent per-task success distribution. Consequently, direct pass@k is identified for k <= n, but generic extrapolated pass@k, tail exponents, and tail constants are not identified for k > n, even with arbitrarily many exchangeable tasks at the same rollout budget. This is stronger than the observation that the usual estimator is undefined beyond n: it characterizes the information missing from the fixed-depth count-law experiment. We give exact count-law-preserving constructions with incompatible extrapolations, state the exceptional unique-extension case, and compute sharp population identified intervals through Hausdorff principal representations. On the public 10,000-rollout-per-problem release of Brown et al., counterfactual n = 16 evaluations leave failure at k = 1000 ambiguous by factors from 1.5 to over 2,600 across four MATH/GSM8K/CodeContests configurations. The calibration shows that intermediate-scale failure share alone does not determine width. Our result does not reject parametric inference-time scaling laws; it supplies the nonparametric baseline against which their assumptions can be evaluated. We give an exact, conservative one-coordinate finite-task confidence certificate and a reporting standard separating direct estimates, identified sets, and model-conditioned forecasts.

Authors 2

Pranav Singh, Prashant Singh

Specification

Official page

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

Arxiv announce type
cross

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

arXiv id
2609.09245

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

Categories
stat.ML, cs.AI, cs.LG

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

PDF

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

Primary category
stat.ML

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

Published
11 Sept 2026

Source:arXiv (Atom API + RSS)T1observed 51 min agohigh

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Provenance

Attributed facts

9

Source tiers

T19

Freshest observation

51 min ago

Conflicts

None