The CHSH urn model is an urn with slips of paper, each containing four numbers -1/+1. Alice randomly (coin toss) picks one of two settings a1 or a2, and Bob randomly picks one of two settings b1 or b2. A slip is then drawn from the urn, and Alice records one of the first two numbers according to her setting a1 or a2, while Bob does the same with the last two numbers according to his setting b1 or b2. The slip is then put back into the urn. We also assume there is nothing spooky going on, so everything behaves according to the standard rules of chance.

When we perform this experiment, each trial results in a setting and an outcome for Alice and a setting and an outcome for Bob. After the experiment is done, we can split the collected data from the N trials into four groups according to the four possible pairs of settings chosen in each trial. For each group, one can then compute the correlation (meaning here: the average of the products).

This particular random experiment is called "the CHSH urn model" because many people believe that the results will satisfy the Bell-CHSH inequality.

One can of course easily simulate the model, too.

Let's discuss whether or not the Bell-CHSH inequality will hold, and let's do some situation experiments to test any claims which people make.

Let's also discuss whether or not this model has anything to do with real Bell experiments and with simulations of Bell experiments.