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name: inference-predictive description: "Run, configure, validate, and troubleshoot PyMC inference and predictive workflows." disable-model-invocation: true metadata: disco-role: operating license: NOASSERTION

PyMC inference and predictive workflows

Use this sub-skill when the task is to run or debug PyMC posterior inference, NUTS/MCMC configuration, explicit step methods, external NUTS backends, prior or posterior predictive sampling, pm.draw, SMC, diagnostics, or trace/output backends.

Runtime map

• Read references/inference-workflows.md for MCMC/NUTS, explicit step methods, external NUTS, prior/posterior predictive sampling, pm.draw, SMC, and diagnostics.
• Read references/api-reference.md for PyMC 6.3.0 signatures, parameter names, sampler kwargs, and output expectations.
• Read references/backends-and-outputs.md for DataTree/ArviZ outputs, log-likelihood, Zarr, mcbackend, and legacy MultiTrace paths.
• Read references/troubleshooting.md for sampling, predictive, external sampler, diagnostics, shape/coord, JAX, Zarr, or mcbackend failures.
• Run scripts/inference_smoke.py to verify a local PyMC install with a tiny CPU model and output-group checks.

Default stance

1. Prefer default return_inferencedata=True and work with DataTree groups such as posterior, sample_stats, posterior_predictive, predictions, and log_likelihood.
2. For reproducible local smokes, callbacks, custom traces, or mixed discrete/continuous models, pin nuts_sampler="pymc".
3. With nuts_sampler=None, current PyMC may auto-select nutpie if installed and compatible. Pin the sampler explicitly when backend choice matters.
4. External NUTS (nutpie, numpyro, blackjax) is for all-continuous differentiable models and does not support custom trace, per-draw callback, or return_inferencedata=False.
5. Use pm.sample_prior_predictive(draws=...), not older samples=....
6. Validate real inference with divergences, tree depth, ESS, R-hat, sample size, and log-likelihood/model-comparison readiness.

Route model/data design to ../modeling-data/SKILL.md, custom distributions/logp to ../distributions-logprob/SKILL.md, and VI/ADVI/SVGD to ../advanced-workflows/SKILL.md.