cross-posted on the EA Forum
I'm interested in questions of the form, "I have a bit of metadata/structure to the question, but I know very little about the content of the question (or alternatively, I'm too worried about biases/hacks to how I think about the problem or what pieces of information to pay attention to). In those situations, what prior should I start with?"
I'm not sure if there is a more technical term than "low-information prior."
Some examples of what I found useful recently:
1. Laplace's Rule of Succession, for when the underlying mechanism is unknown.
2. Percentage of binary questions that resolves as "yes" on Metaculus. It turns out that of all binary (Yes-No) questions asked on the prediction platform Metaculus, 29% of them resolved yes. This means that even if you know nothing about the content of a Metaculus question, a reasonable starting point for answering a randomly selected binary Metaculus question is 29%.
In both cases, obviously there are reasons to override the prior (for example, you can arbitrarily flip all questions on Metaculus such that your prior is now 71%). However (I claim), having a decent prior is nonetheless useful in practice, even if it's theoretically unprincipled.
I'd be interested in seeing something like 5-10 examples of low-information priors as useful as the rule of succession or the Metaculus binary prior.
The Lindy effect (or Lindy's Law).
Example: you have two books to choose from (assuming both seem equally interesting), and you don't know much information about them except how long they've been in print. The first one came out this year, and the other one has been in print for 40 years.
Using Lindy you can expect the first book's sales to drop either this year or the next one, and you can expect the latter to stay in print for about 40 more years. in other words, the older book is likely to be more relevant, and so that's the one you'll choose.
I suggest Nassim Taleb's 'Antifragile' if you wish to read more about it.
That's not true, because one's lifespan is limited. If you're constantly focusing on the timely, you in fact will not have time for the timeless.