@inproceedings{wang-2026-probing,
title = "Probing Pretraining ``Quality'': Sociolinguistic Mobility as a Lens on Web Corpus Filters",
author = "Wang, Jessica",
editor = "Ortiz Suarez, Pedro and
Burchell, Laurie and
Ljube{\v{s}}i{\'c}, Nikola and
Scherrer, Yves and
Laippala, Veronika and
Dini{\'c}, Vuk and
Vaughan, Thom",
booktitle = "Proceedings of the 13th Web-as-Corpus Workshop",
month = oct,
year = "2026",
address = "Budapest, Hungary",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.wac-1.28/",
pages = "320--330",
ISBN = "979-8-89176-481-1",
abstract = "Data selection algorithms for large language model (LLM) pretraining are designed to mine `quality' from the web, but that notion is murky at best. This study explores whether sociolinguistic mobility {--} realized through language use, in context {--} offers a lens for understanding what such algorithms actually select. As a case study, the FineWeb pretraining pipeline is examined for how it reshapes two tangible axes of language use: the geographical provenance and register composition of texts drawn from ICE and GloWbE.\par FineWeb rejection rates are highest, and fairly uniform across provenance groups, for web-native and high-context registers (90.9{\%} and 99.2{\%}, respectively) but within medium-context registers, association with the United States is moderately protective: the 7{\%} rejection rate is well below the medium-context average of 38{\%}, an effect corroborated by NPMI. Unlike prior work on learned, classifier-based filters and US-internal sociolect bias, this study finds comparable effects in a deterministic pipeline within the global spread of English. As pretraining data selection becomes increasingly opaque, these results suggest that algorithmic `quality' does not represent a real-world range of English use manifested in the web-as-corpus {--} a gap made visible by tangible sociolinguistic dimensions."
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<abstract>Data selection algorithms for large language model (LLM) pretraining are designed to mine ‘quality’ from the web, but that notion is murky at best. This study explores whether sociolinguistic mobility – realized through language use, in context – offers a lens for understanding what such algorithms actually select. As a case study, the FineWeb pretraining pipeline is examined for how it reshapes two tangible axes of language use: the geographical provenance and register composition of texts drawn from ICE and GloWbE.\par FineWeb rejection rates are highest, and fairly uniform across provenance groups, for web-native and high-context registers (90.9% and 99.2%, respectively) but within medium-context registers, association with the United States is moderately protective: the 7% rejection rate is well below the medium-context average of 38%, an effect corroborated by NPMI. Unlike prior work on learned, classifier-based filters and US-internal sociolect bias, this study finds comparable effects in a deterministic pipeline within the global spread of English. As pretraining data selection becomes increasingly opaque, these results suggest that algorithmic ‘quality’ does not represent a real-world range of English use manifested in the web-as-corpus – a gap made visible by tangible sociolinguistic dimensions.</abstract>
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%0 Conference Proceedings
%T Probing Pretraining “Quality”: Sociolinguistic Mobility as a Lens on Web Corpus Filters
%A Wang, Jessica
%Y Ortiz Suarez, Pedro
%Y Burchell, Laurie
%Y Ljubešić, Nikola
%Y Scherrer, Yves
%Y Laippala, Veronika
%Y Dinić, Vuk
%Y Vaughan, Thom
%S Proceedings of the 13th Web-as-Corpus Workshop
%D 2026
%8 October
%I Association for Computational Linguistics
%C Budapest, Hungary
%@ 979-8-89176-481-1
%F wang-2026-probing
%X Data selection algorithms for large language model (LLM) pretraining are designed to mine ‘quality’ from the web, but that notion is murky at best. This study explores whether sociolinguistic mobility – realized through language use, in context – offers a lens for understanding what such algorithms actually select. As a case study, the FineWeb pretraining pipeline is examined for how it reshapes two tangible axes of language use: the geographical provenance and register composition of texts drawn from ICE and GloWbE.\par FineWeb rejection rates are highest, and fairly uniform across provenance groups, for web-native and high-context registers (90.9% and 99.2%, respectively) but within medium-context registers, association with the United States is moderately protective: the 7% rejection rate is well below the medium-context average of 38%, an effect corroborated by NPMI. Unlike prior work on learned, classifier-based filters and US-internal sociolect bias, this study finds comparable effects in a deterministic pipeline within the global spread of English. As pretraining data selection becomes increasingly opaque, these results suggest that algorithmic ‘quality’ does not represent a real-world range of English use manifested in the web-as-corpus – a gap made visible by tangible sociolinguistic dimensions.
%U https://aclanthology.org/2026.wac-1.28/
%P 320-330
Markdown (Informal)
[Probing Pretraining “Quality”: Sociolinguistic Mobility as a Lens on Web Corpus Filters](https://aclanthology.org/2026.wac-1.28/) (Wang, WAC 2026)
ACL