This isn’t a thing per se.
But I want a landing page for a few different ways
to think about hidden variablesand unobserved states.
If the hidden variables are random, I might think of hierarchical models,
latent factors, deep networks, informative sampling, censored data,
weak supervision …
If the hidden variables are deterministic I might think of
Matrix factorisation to approximate latent factors
and their interaction in recommender systems.