Think of a prior as what&#x27;s plausible or not plausible given the current state of our knowledge, rather than as an objective state of the world.<p>Mind you, that doesn&#x27;t mean priors are necessarily subjective.<p>In medicine, we often have information about the prevalence of diseases, which gives us a prior that we can take into account when looking at the result of a test: if someone tests positive on an incredibly rare disease, chances are the test is wrong because the prior probability of having the disease is so exceedingly low.<p>In psychology, if you read research that claims to have found statistically significant evidence for extrasensory perception, you might not believe that straight away, because it contradicts everything we know about the physical universe and thus is a priori very improbable.<p>In marketing, if you&#x27;re doing an A&#x2F;B-test where you change some body copy, in the very best case you might get a 100% increase in conversion, but certainly not a 100,000,000% increase. A prior can be as subtle as &quot;no effect is a tiny bit more likely than an effect of 10^12&quot; and this can be enough to get better estimates when you have very little data.<p>Your interpretation is not unusual, though: in frequentist statistics, parameters are considered fixed values and as such not something you can assign a probability.