Posterior predictive checks

[maxbiostat]

One of the things we should be doing when comparing priors is:

• Prior predictive checks: what sort of trajectory I(t) [or R(t)] does a particular prior on R0 or beta and gamma induce;
  and
• Posterior predictive checks: sure, a prior might change the posterior slightly or even a lot, but what is the effect on the predicted quantities of the model, such as the time to peak incidence or the trajectory R(t)?