Google Meridian (verified against v1.8.0)

Meridian is Google's open-source Bayesian MMM: TensorFlow Probability, geo-hierarchical by default, with media effects parameterised by ROI rather than by coefficient. That last choice is the important one — the prior sits directly on the quantity stakeholders argue about.

Install: pip install google-meridian (Python ≥ 3.10; pulls TensorFlow 2.21 and a pinned tfp-nightly). GPU: google-meridian[and-cuda]. There is also a [jax] extra.