Why and When to Use Statistical Significance in Explanation Evaluation: A Systematic Survey and Guidelines for Explainable NLP

Fariz Ikhwantri, Dusica Marijan


Abstract
In this paper, we present a systematic survey and methodological guidelines for explanation evaluation and statistical significance testing in explainable NLP (XAI). We systematically reviewed 494 verified papers from the ACL Anthology (2020–2025) to identify how explanations are evaluated and the frequency of statistical validation. Our analysis identifies a persistent **rigour gap**: although **the number of explainable NLP papers increased fivefold** during the study period, there was **no corresponding increase in the use of explanation-specific statistical testing**. Across the full corpus, only 25.30% (125/494) of studies substantiate evaluation claims with hypothesis testing. This remains a minority practice in every surveyed year. We categorise the primary barriers to rigour into three issues: implicit generalisation, inferential reporting gap, and incomplete rigour. To address these, we propose a bipartite framework that maps research hypotheses to appropriate statistical testing regimes. Our goal is to clarify when statistical testing is necessary and to provide a guideline for more rigorous, reproducible explainability research in the LLM era.
Anthology ID:
2026.emnlp-main.504
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
11571–11595
Language:
URL:
https://aclanthology.org/2026.emnlp-main.504/
DOI:
Bibkey:
Cite (ACL):
Fariz Ikhwantri and Dusica Marijan. 2026. Why and When to Use Statistical Significance in Explanation Evaluation: A Systematic Survey and Guidelines for Explainable NLP. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 11571–11595, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Why and When to Use Statistical Significance in Explanation Evaluation: A Systematic Survey and Guidelines for Explainable NLP (Ikhwantri & Marijan, EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.504.pdf