How can I choose an explainer? An Application-grounded Evaluation of Post-hoc Explanations

Abstract

There have been several research works proposing new Explainable AI (XAI) methods designed to generate model explanations having specific properties, or desiderata, such as fidelity, robustness, or human-interpretability. However, explanations are seldom evaluated based on their true practical impact on decision-making tasks. Without that assessment, explanations might be chosen that, in fact, hurt the overall performance of the combined system of ML model + end-users. This study aims to bridge this gap by proposing XAI Test, an application-grounded evaluation methodology tailored to isolate the impact of providing the end-user with different levels of information. We conducted an experiment following XAI Test to evaluate three popular post-hoc explanation methods -- LIME, SHAP, and TreeInterpreter -- on a real-world fraud detection task, with real data, a deployed ML model, and fraud analysts. During the experiment, we gradually increased the information provided to the fraud analysts in three stages: Data Only, i.e., just transaction data without access to model score nor explanations, Data + ML Model Score, and Data + ML Model Score + Explanations. Using strong statistical analysis, we show that, in general, these popular explainers have a worse impact than desired. Some of the conclusion highlights include: i) showing Data Only results in the highest decision accuracy and the slowest decision time among all variants tested, ii) all the explainers improve accuracy over the Data + ML Model Score variant but still result in lower accuracy when compared with Data Only; iii) LIME was the least preferred by users, probably due to its substantially lower variability of explanations from case to case.

Accepted at FAccT'21, the ACM Conference on Fairness, Accountability, and Transparency

References in corpus (6)

• Towards A Rigorous Science of Interpretable Machine Learning
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• Quantifying Interpretability and Trust in Machine Learning Systems
• The Doctor Just Won't Accept That!
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Cited by in corpus (4)

• Fairness via Explanation Quality: Evaluating Disparities in the Quality of Post hoc Explanations
• What Does Evaluation of Explainable Artificial Intelligence Actually Tell Us? A Case for Compositional and Contextual Validation of XAI Building Blocks
• How Can We Develop Explainable Systems? Insights from a Literature Review and an Interview Study
• Pitfalls of Explainable ML: An Industry Perspective