2.9 Summary

Although Bayesian statistics is conceptually simple, fully probabilistic models often lead to analytically intractable expressions. For many years, this was a huge barrier, hindering the wide adoption of Bayesian methods. Fortunately, maths, statistics, physics, and computer science came to the rescue in the form of numerical methods that are capable—at least in principle—of solving any inference problem. The possibility of automating the inference process has led to the development of probabilistic programming languages, allowing a clear separation between model definition and inference. PyMC is a Python library for probabilistic programming with a very simple, intuitive, and easy-to-read syntax that is also very close to the statistical syntax used to describe probabilistic models.

We introduced the PyMC library by revisiting the coin-flip model from Chapter 1, this time without analytically deriving the posterior. PyMC models are defined inside a context manager...