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Train, Evaluate, Repeat: Building a Credit Card Fraud Detection System

Talkat PyData Los Angeles 2018 · 2018-10-17..10-19· [machine-learning, security]
links:none on file
slides:none on file

Describes concrete solutions for Stripe’s fraud stack: chooses merchant‑agnostic labels like chargebacks and issuer fraud records, experiments to set a 10% target rate for positives instead of fixed downsampling, and implements a uniform holdback group (random X%) to get unbiased labels. Uses gradient‑boosted trees and scikit‑learn sample weights, handles <1% fraud prevalence, retrains frequently, and shows the holdback reduces estimator variance and preserves long‑term performance.

AI-written summary · about

  1. 0:00Stripe and credit card fraud
  2. 3:26Defining fraud impact
  3. 7:00Labeling fraud data challenges
  4. 12:05Class imbalance handling
  5. 19:38Training data target rates
  6. 23:17Counterfactual evaluation
  7. 35:46Key takeaways and optimization
  8. 37:10Q&A
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