Prosa: Rubric-Based Evaluation of LLMs on Real User Chats in Brazilian Portuguese

Fuente: arXiv
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Autori principali: Junior, Roseval Malaquias, Bonás, Giovana Kerche, Almeida, Thales Sales, Abonizio, Hugo, Laitz, Thiago, Pires, Ramon, Piau, Marcos, Larcher, Celio, Nogueira, Rodrigo
Natura: Preprint
Pubblicazione: 2026
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author Junior, Roseval Malaquias
Bonás, Giovana Kerche
Almeida, Thales Sales
Abonizio, Hugo
Laitz, Thiago
Pires, Ramon
Piau, Marcos
Larcher, Celio
Nogueira, Rodrigo
author_facet Junior, Roseval Malaquias
Bonás, Giovana Kerche
Almeida, Thales Sales
Abonizio, Hugo
Laitz, Thiago
Pires, Ramon
Piau, Marcos
Larcher, Celio
Nogueira, Rodrigo
contents Rankings produced by holistic LLM-as-a-judge scoring are sensitive to the bias of the chosen judge model. We show that switching to binary rubric scoring with multi-judge filtering removes this sensitivity: decomposing the judgement matters more than the judge model itself. To support this claim, we introduce Prosa, the first real user multi-turn Brazilian Portuguese chat benchmark: 1,000 WildChat conversations scored by three judges from three model families on 16 models. Under filtered rubric scoring the three judges agree on every one of the 16 ranks, whereas under holistic scoring they agree on only 7 of 16. Additionally, the rubric filtering pipeline increases the average score gap between neighbouring models by 47%, thereby improving Prosa's discriminative power. Evaluating a new model on Prosa costs approximately $2.1 when using Gemini 3 Flash as the judge. We release the benchmark and the filtering code to ensure that future models can be assessed under identical conditions. These artifacts also make our rubric-based scoring method reusable beyond Prosa, supporting other open-ended evaluation settings.
format Preprint
id arxiv_https___arxiv_org_abs_2605_01630
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Prosa: Rubric-Based Evaluation of LLMs on Real User Chats in Brazilian Portuguese
Junior, Roseval Malaquias
Bonás, Giovana Kerche
Almeida, Thales Sales
Abonizio, Hugo
Laitz, Thiago
Pires, Ramon
Piau, Marcos
Larcher, Celio
Nogueira, Rodrigo
Computation and Language
Artificial Intelligence
Rankings produced by holistic LLM-as-a-judge scoring are sensitive to the bias of the chosen judge model. We show that switching to binary rubric scoring with multi-judge filtering removes this sensitivity: decomposing the judgement matters more than the judge model itself. To support this claim, we introduce Prosa, the first real user multi-turn Brazilian Portuguese chat benchmark: 1,000 WildChat conversations scored by three judges from three model families on 16 models. Under filtered rubric scoring the three judges agree on every one of the 16 ranks, whereas under holistic scoring they agree on only 7 of 16. Additionally, the rubric filtering pipeline increases the average score gap between neighbouring models by 47%, thereby improving Prosa's discriminative power. Evaluating a new model on Prosa costs approximately $2.1 when using Gemini 3 Flash as the judge. We release the benchmark and the filtering code to ensure that future models can be assessed under identical conditions. These artifacts also make our rubric-based scoring method reusable beyond Prosa, supporting other open-ended evaluation settings.
title Prosa: Rubric-Based Evaluation of LLMs on Real User Chats in Brazilian Portuguese
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2605.01630