Cited by 3,735Computational Drug Discovery MethodsMachine Learning in Materials ScienceAdvanced Chemical Physics Studies

Beware of q2!

Golbraikh, Alexander, Tropsha, Alexander·2002·Journal of Molecular Graphics and Modelling

Abstract

Validation is a crucial aspect of any quantitative structure-activity relationship (QSAR) modeling. This paper examines one of the most popular validation criteria, leave-one-out cross-validated R2 (LOO q2). Often, a high value of this statistical characteristic (q2 > 0.5) is considered as a proof of the high predictive ability of the model. In this paper, we show that this assumption is generally incorrect. In the case of 3D QSAR, the lack of the correlation between the high LOO q2 and the high predictive ability of a QSAR model has been established earlier [Pharm. Acta Helv. 70 (1995) 149; J. Chemomet. 10(1996)95; J. Med. Chem. 41 (1998) 2553]. In this paper, we use two-dimensional (2D) molecular descriptors and k nearest neighbors (kNN) QSAR method for the analysis of several datasets. No correlation between the values of q2 for the training set and predictive ability for the test set was found for any of the datasets. Thus, the high value of LOO q2 appears to be the necessary but not the sufficient condition for the model to have a high predictive power. We argue that this is the general property of QSAR models developed using LOO cross-validation. We emphasize that the external validation is the only way to establish a reliable QSAR model. We formulate a set of criteria for evaluation of predictive ability of QSAR models.

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Crossref · 10.1016/s1093-3263(01)00123-1

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  • QSAR modeling was one of the first research fields that highlighted the importance of data curation, rigorous validation of developed models, and data reproducibility.

    “Importantly, QSAR modeling was one of the first research fields that highlighted the importance of data curation,13 rigorous validation of developed models,14 and data reproducibility,15 that has recently become a significant concern to the scientific community.16”

    From QSAR without borders (2020) · cites this paper as [14]

  • Rigorous model validation prior to prediction and the importance of rigor in modeling protocols have been articulated in seminal QSAR publications and have already been adopted as regulatory requirements.

    “Similarly, rigorous model validation prior to prediction14 and the importance of rigor in modeling protocols291 have been articulated in several seminal publications in QSAR field292 and have already been adopted as regulatory requirements.84”

    From QSAR without borders (2020) · cites this paper as [14]

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Authors
Golbraikh, A., & Tropsha, A.
Affiliations
University of North Carolina at Chapel Hill (US)
Corresponding author
Tropsha, Alexander
Venue
Journal of Molecular Graphics and Modelling
Publisher
Elsevier BV
Published
2002-01
Volume
20
Issue
4
Pages
269-276
ISSN
1093-3263 (ISSN-L)
OpenAlex
W2087661061
Cited by
3,735
References
39
Citations by year
2026: 133 · 2025: 164 · 2024: 179 · 2023: 174 · 2022: 194 · 2021: 197 · 2020: 215 · 2019: 189 · 2018: 200 · 2017: 174 · 2016: 181 · 2015: 175 · 2014: 197 · 2013: 203 · 2012: 202
FWCI
52.71
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Molecular Graphics and Modelling (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Physical Sciences › Computer Science › Computational Theory and Mathematics › Computational Drug Discovery Methods
  • Physical Sciences › Materials Science › Materials Chemistry › Machine Learning in Materials Science
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Advanced Chemical Physics Studies
Keywords
leave-one-out cross-validation, QSAR model validation, predictive power, external validation, 2D molecular descriptors, overfitting, model evaluation metrics
MeSH terms
Data Interpretation, Statistical, Ligands, Mathematical Computing, Models, Molecular, Receptors, Histamine H1, Steroids, Transcortin, Databases, Factual, Quantitative Structure-Activity Relationship, Ecdysteroids

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