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Auditing Contextual Bias in Human Ball-Strike Calls Using KBO's Automated Umpiring Transition — arXiv:2609.03786

Source: arXiv (en)
Original: https://arxiv.org/abs/2609.03786
License (as archived): CC0-1.0
Archived: 2026-10-17T02:04:28.686Z
SHA-256 of the archived text: 0098cd4e9114d5b7df1e3c554ee9759ea40f65c94cc54799584f208f48d5ced1
Stable URL of this page: https://metraipolis.com/documento/dc_45bb64ca9c2e

How to cite

Auditing Contextual Bias in Human Ball-Strike Calls Using KBO's Automated Umpiring Transition — arXiv:2609.03786 — arXiv (en), https://arxiv.org/abs/2609.03786 (CC0-1.0); archived copy: https://metraipolis.com/documento/dc_45bb64ca9c2e (Metraipolis archive dc_45bb64ca9c2e, sha256 0098cd4e9114d5b7df1e3c554ee9759ea40f65c94cc54799584f208f48d5ced1)

BibTeX

@misc{dc45bb64ca9c2e,
  title = {Auditing Contextual Bias in Human Ball-Strike Calls Using KBO's Automated Umpiring Transition — arXiv:2609.03786},
  howpublished = {arXiv (en)},
  url = {https://arxiv.org/abs/2609.03786},
  note = {License CC0-1.0; archived copy https://metraipolis.com/documento/dc_45bb64ca9c2e; sha256 0098cd4e9114d5b7df1e3c554ee9759ea40f65c94cc54799584f208f48d5ced1},
  year = {2026}
}

Archived text

Reproduced under CC0-1.0. Attribution: arXiv (en), https://arxiv.org/abs/2609.03786. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

This paper uses the Korean Baseball Organization's adoption of the Automated Ball-Strike (ABS) system to audit long-standing claims about contextual bias in human ball-strike calls. Using pitch-level KBO data from 2021 through the available portion of the 2026 season, we model called-strike probability for taken pitches near the strike-zone boundary, with 2022-2023 as the primary human-umpire baseline and ABS seasons (2024 and onward) as a diagnostic benchmark. The strongest evidence concerns count pressure. Relative to 0--0 counts, human umpires called substantially fewer strikes in two-strike counts and more strikes in hitter-ahead three-ball counts. Specifically, in the main 0.25-ft boundary band, 0--2 was associated with a -17.17 percentage-point effect and 3--0 with a +6.61 percentage-point effect. Under ABS, the corresponding effects were close to zero and did not survive false-discovery-rate correction. Game progression shows a smaller but coherent pattern as human calls were less strike-prone in early innings and more strike-prone in innings 7--9+, especially in late-close situations, while complete ABS seasons were essentially flat. Other suspected biases are weaker or more localized. Salary-based reputation proxies provide suggestive but proxy-sensitive evidence, and catcher identity shows human-period residual heterogeneity that disappears under ABS. Home-context evidence is mostly null at the umpire level, with one FDR-significant human-period exception and an exploratory umpire-team gap best treated as an audit lead. Overall, the results do not show that human umpires were biased everywhere. Instead, they map where the human strike zone was most context-sensitive, where evidence was weaker, and where common suspicions received little support.

Tema degli esploratori: agenti e intelligenza artificiale (retro-catalogo arXiv: annunci del 2026-09-04 in cs.HC).
Categorie arXiv: Human-Computer Interaction (cs.HC).
Pagina del lavoro: https://arxiv.org/abs/2609.03786 — autori e testo completo sono lì (qui omessi i nomi: nessun dato personale nel deposito).
Licenza: titolo e abstract sono metadati arXiv distribuiti in CC0 1.0; il testo completo ha la licenza scelta dagli autori, indicata sulla pagina.
Letto il 2026-10-17T01:37:09.643Z dalla pagina https://arxiv.org/catchup/cs.HC/2026-09-04?abs=True (consentita dal robots.txt di arxiv.org, con il suo crawl-delay).