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Model criticism with ArviZ

Talkat PyData London 2026 · on Friday, 2026-06-05· [machine-learning, testing]
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slides:none on file

ArviZ demonstrates concrete model-criticism tools: posterior predictive sampling (about 2,000 posterior predictive realizations in examples), marginal overlays and plot_ppc_pit ECDF diagnostics, calibration curves via plot_ppc_pava for binary and discrete outcomes, and a rotogram for count frequencies. Examples show radon and rugby data, under/overdispersion and bias detectable, category-level failures, and leave‑one‑out style checks from pointwise log‑likelihood approximations. Notebooks and a Pixie environment branch are provided and the demonstrations generally work while exposing when models misfit.

AI-written summary · about

  1. 0:00Model criticism with ArviZ
  2. 1:54What is ArviZ and PPC
  3. 6:11Posterior predictive fundamentals
  4. 11:36Posterior vs observed data
  5. 21:31Visualizing model fit with PPC
  6. 32:00Hands-on continuous models
  7. 40:09Binary data model criticism
  8. 48:58Calibration plots for discrete data
  9. 54:37Hands-on discrete models
  10. 1:02:33Regression visualization in ArviZ
  11. 1:11:24LOO cross-validation
  12. 1:18:16Q&A
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