Google Professional Machine Learning Engineer
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You are a Machine Learning Engineer at a utility company tasked with improving the detection of defects in underground electric cables using thermal imaging. Your dataset comprises 10,000 thermal images, with a mere 100 images containing visible defects, making the dataset highly imbalanced. The company requires a robust evaluation method that not only assesses the model's ability to correctly identify defects but also considers the implications of false positives in a real-world maintenance scenario where unnecessary excavations could lead to significant costs and operational disruptions. Given these constraints, which of the following methods is the most effective for evaluating your model's performance on a test dataset? Choose the best option.
Explanation:
The correct approach is to Assess the Area Under the Curve (AUC) value of the ROC curve. This method is ideal for several reasons:
Imbalanced Dataset Handling: AUC is particularly effective for evaluating models on imbalanced datasets, as it considers the balance between true positive rates and false positive rates across all classification thresholds.
Comprehensive Evaluation: AUC provides a single metric that summarizes the model's ability to discriminate between the positive (defective) and negative (non-defective) classes, making it easier to compare different models or approaches.
Operational Relevance: Given the operational constraints and the high cost of false positives, AUC offers a nuanced view of the model's performance that aligns with the company's need to minimize unnecessary maintenance actions.
Additionally, implementing a combination of precision-recall curves and F1 score (Option E) is also a valid approach, especially when the cost of false positives is high. This method focuses on the balance between precision (the accuracy of the positive predictions) and recall (the ability to find all positive instances), providing a more granular view of the model's performance in scenarios where the positive class is rare but important to identify correctly.