University of Oulu

Alasalmi Tuomo, Jaakko Suutala, Juha Röning, and Heli Koskimäki. 2020. Better Classifier Calibration for Small Datasets. ACM Trans. Knowl. Discov. Data 14, 3, Article 34 (May 2020), 19 pages. DOI:

Better classifier calibration for small datasets

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Author: Alasalmi, Tuomo1; Suutala, Jaakko1; Röning, Juha1;
Organizations: 1University of Oulu, Finland
2Oura Health Ltd., Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 0.6 MB)
Persistent link:
Language: English
Published: Association for Computing Machinery, 2020
Publish Date: 2020-05-27


Classifier calibration does not always go hand in hand with the classifier’s ability to separate the classes. There are applications where good classifier calibration, i.e., the ability to produce accurate probability estimates, is more important than class separation. When the amount of data for training is limited, the traditional approach to improve calibration starts to crumble. In this article, we show how generating more data for calibration is able to improve calibration algorithm performance in many cases where a classifier is not naturally producing well-calibrated outputs and the traditional approach fails. The proposed approach adds computational cost but considering that the main use case is with small datasets this extra computational cost stays insignificant and is comparable to other methods in prediction time. From the tested classifiers, the largest improvement was detected with the random forest and naive Bayes classifiers. Therefore, the proposed approach can be recommended at least for those classifiers when the amount of data available for training is limited and good calibration is essential.

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Series: ACM transactions on knowledge discovery from data
ISSN: 1556-4681
ISSN-E: 1556-472X
ISSN-L: 1556-4681
Volume: 14
Issue: 3
Pages: 1 - 19
Article number: 34
DOI: 10.1145/3385656
Type of Publication: A1 Journal article – refereed
Field of Science: 113 Computer and information sciences
Funding: The authors would like to thank Infotech Oulu, Jenny and Antti Wihuri Foundation, Tauno Tönning Foundation, and Walter Ahlström Foundation for financial support of this work.
Copyright information: © 2020 Association for Computing Machinery. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in ACM Transactions on Knowledge Discovery from Data,