The numerical value of the prior itself doesn't tell how much information -- or lack thereof -- is incorporated into the prior.

What's a simple way to state how certain you are about a prior, i.e. how stable it is against large updates based on new information? Error bars or something related don't necessarily do the job -- you might be very sure that the true Pr (EDIT: that was poorly phrased, probability is in the mind etc., what was meant is the eventual Pr you end up with once you've hypothetically parsed all possible information, the limit) is between ... (read more)