placebo_in_time#

Placebo-in-time sensitivity check with hierarchical null model.

Builds a hierarchical Bayesian model of the “status quo” (no-effect) distribution from placebo folds, then compares the actual intervention effect against that learned null. Optionally computes Bayesian assurance (operating characteristics) against a user-supplied expected-effect prior.

Supports two fold-selection strategies:

  • sequential (default) — evenly-spaced sliding windows stepping backward from the actual treatment time.

  • random — randomly sampled eligible windows from the pre-intervention period, with constraints on minimum training fraction, minimum gap between folds, and optional period exclusion.

Supports experiments with a treatment_time parameter (InterruptedTimeSeries, SyntheticControl). Requires a PyMC model for posterior extraction.

Classes

AssuranceResult

Bayesian operating characteristics from design-level simulation.

PlaceboFoldResult

Result of a single placebo fold.

PlaceboInTime

Placebo-in-time sensitivity check with hierarchical null model.