liveBook · Manning

Semi-supervised learning

As explained in Financial AI in Practice

Semi-supervised learning uses a limited amount of labeled data together with a larger pool of unlabeled data.

Fraud detection often has few labeled fraud cases but many unlabeled transactions. Semi-supervised learning uses both: a small labeled set guides learning from a much larger, mostly legitimate unlabeled pool. This can reduce reliance on expensive manual labeling and expose the model to more data patterns. section 7.4.3

Two common approaches differ in how they use unlabeled transactions:

  • Self-training: train on labeled data, predict labels for unlabeled transactions, add high-confidence predictions to the labeled set, then retrain. section 7.4.3
  • Co-training: train multiple models, often on different feature subsets, and use their confident or agreeing predictions to label unlabeled instances. section 7.4.3

How Financial AI in Practice covers it

How deep it goes
Defines the approach and outlines self-training and co-training procedures, without specifying an implementation or evaluation protocol.
Examples
Uses fraud transactions to illustrate how high-confidence predictions can expand a labeled set.
What it assumes
Assumes familiarity with labeled transaction data and supervised fraud detection while defining how unlabeled data enters the workflow.
What you can do after
Evaluate/understand when scarce fraud labels and abundant unlabeled transactions make self-training or co-training worth considering.
How it connects
Connects supervised learning, class imbalance, self-training, co-training, and synthetic data augmentation as responses to scarce fraud labels.

Also explained in

Compare how 5 books explain semi-supervised learning →

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Financial AI in Practice. The section links point to the parts of the book it draws on.