Evaluating the Evaluation of Diversity in Natural Language Generation

Guy Tevet, Jonathan Berant


Abstract
Despite growing interest in natural language generation (NLG) models that produce diverse outputs, there is currently no principled method for evaluating the diversity of an NLG system. In this work, we propose a framework for evaluating diversity metrics. The framework measures the correlation between a proposed diversity metric and a diversity parameter, a single parameter that controls some aspect of diversity in generated text. For example, a diversity parameter might be a binary variable used to instruct crowdsourcing workers to generate text with either low or high content diversity. We demonstrate the utility of our framework by: (a) establishing best practices for eliciting diversity judgments from humans, (b) showing that humans substantially outperform automatic metrics in estimating content diversity, and (c) demonstrating that existing methods for controlling diversity by tuning a “decoding parameter” mostly affect form but not meaning. Our framework can advance the understanding of different diversity metrics, an essential step on the road towards better NLG systems.
Anthology ID:
2021.eacl-main.25
Volume:
Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume
Month:
April
Year:
2021
Address:
Online
Editors:
Paola Merlo, Jorg Tiedemann, Reut Tsarfaty
Venue:
EACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
326–346
Language:
URL:
https://aclanthology.org/2021.eacl-main.25
DOI:
10.18653/v1/2021.eacl-main.25
Bibkey:
Cite (ACL):
Guy Tevet and Jonathan Berant. 2021. Evaluating the Evaluation of Diversity in Natural Language Generation. In Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume, pages 326–346, Online. Association for Computational Linguistics.
Cite (Informal):
Evaluating the Evaluation of Diversity in Natural Language Generation (Tevet & Berant, EACL 2021)
Copy Citation:
PDF:
https://aclanthology.org/2021.eacl-main.25.pdf
Code
 GuyTevet/diversity-eval