False positive rate explained: a complete guide for ML teams (February 2026)

Understanding and managing the false positive rate (FPR) is crucial for machine learning (ML) teams, as it measures the rate at which models incorrectly flag negative instances as positive, calculated by the formula FPR = FP / (FP + TN). High FPRs can overwhelm investigation teams, erode trust, and lead to significant business costs across various industries, such as anti-money laundering and healthcare diagnostics. Effective management of FPR involves adjusting decision thresholds according to cost ratios, resampling imbalanced data, adding contextual features, and deploying ensemble methods. Continuous evaluation is essential in production environments to adapt to data shifts and maintain actionable alert levels, with strategies including monitoring across different cohorts and feedback loops from investigation outcomes. The balance between false positive and false negative rates is a key consideration, with the ROC curve helping to visualize tradeoffs; the goal is not zero false positives but a sustainable rate that supports effective threat detection and investigation capacity.