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Conformal Prediction

Conformal prediction is a framework for quantifying the uncertainty of a model's predictions. Instead of returning only a point prediction, it uses the model's past errors to produce an output that expresses which values or labels remain plausible for a new observation.

MAPIE applies conformal prediction to any scikit-learn-compatible estimator:

  • for regression, it returns a prediction interval around each prediction;
  • for classification, it returns a set of plausible classes.

For example, with a confidence level of 90%, conformal prediction aims for the true value or class to be included in the predicted interval or set for at least 90% of future observations. This is a marginal coverage guarantee: it holds on average over new observations, not necessarily for every subgroup or individual observation.

Explore Conformal Prediction in MAPIE

  • Theory presents the foundational elements of conformal prediction.
  • Regression theory explains prediction intervals and the split, cross-validation, jackknife, and bootstrap-based methods.
  • Classification explains prediction sets and the split- and cross-conformal strategies.
  • Conformity scores describes how MAPIE measures whether a prediction agrees with an observation in regression and classification.
  • Conformalization set compares split- and cross-conformal workflows.
  • Metrics covers coverage, interval width, prediction-set size, and conditional coverage diagnostics.
  • Conditional guarantees introduces methods that go beyond marginal coverage.