Open Access
CC BY-NC-ND 4.0 · Methods Inf Med 2019; 58(S 02): e27-e42
DOI: 10.1055/s-0039-1693732
Original Article
Georg Thieme Verlag KG Stuttgart · New York

Overrating Classifier Performance in ROC Analysis in the Absence of a Test Set: Evidence from Simulation and Italian CARATkids Validation

Giovanna Cilluffo§
1   Institute for Biomedical Research and Innovation, National Research Council of Italy, Palermo, Italy
2   Department of Economical, Business and Statistical Science, University of Palermo, Palermo, Italy
,
Salvatore Fasola§
1   Institute for Biomedical Research and Innovation, National Research Council of Italy, Palermo, Italy
2   Department of Economical, Business and Statistical Science, University of Palermo, Palermo, Italy
,
Giuliana Ferrante
3   Department of Health Promotion Sciences, Maternal and Infant Care, Internal Medicine and Medical Specialities, University of Palermo, Italy
,
Laura Montalbano
1   Institute for Biomedical Research and Innovation, National Research Council of Italy, Palermo, Italy
,
Ilaria Baiardini
4   Department of Biomedical Sciences, Humanitas University, Milan, Italy
,
Luciana Indinnimeo
5   Department of Pediatrics and NPI, University of Roma Sapienza, Rome, Italy
,
Giovanni Viegi
1   Institute for Biomedical Research and Innovation, National Research Council of Italy, Palermo, Italy
6   Institute of Clinical Physiology, Pulmonary Environmental Epidemiology Unit, National Research Council of Italy, Pisa, Italy
,
Joao A. Fonseca
7   Department of Immunoallergy, CUF Porto Hospital and Institute, Porto, Portugal
,
Stefania La Grutta
1   Institute for Biomedical Research and Innovation, National Research Council of Italy, Palermo, Italy
› Author Affiliations

Funding None.
Further Information

Publication History

04 October 2018

21 May 2019

Publication Date:
19 November 2019 (online)

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Abstract

Background The use of receiver operating characteristic curves, or “ROC analysis,” has become quite common in biomedical research to support decisions. However, sensitivity, specificity, and misclassification rates are still often estimated using the training sample, overlooking the risk of overrating the test performance.

Methods A simulation study was performed to highlight the inferential implications of splitting (or not) the dataset into training and test set. The normality assumption was made for the classifier given the disease status, and the Youden's criterion considered for the detection of the optimal cutoff. Then, an ROC analysis with sample split was applied to assess the discriminant validity of the Italian version of the Control of Allergic Rhinitis and Asthma Test (CARATkids) questionnaire for children with asthma and rhinitis, for which recent studies may have reported liberal performance estimates.

Results The simulation study showed that both single split and cross-validation (CV) provided unbiased estimators of sensitivity, specificity, and misclassification rate, therefore allowing computation of confidence intervals. For the Italian CARATkids questionnaire, the misclassification rate estimated by fivefold CV was 0.22, with 95% confidence interval 0.14 to 0.30, indicating an acceptable discriminant validity.

Conclusions Splitting into training and test set avoids overrating the test performance in ROC analysis. Validated through this method, the Italian CARATkids is valid for assessing disease control in children with asthma and rhinitis.

Note

All data and materials are available upon request.


§ These two authors contributed equally.


Supplementary Material