Are those questions on-topic for the OR stackexchange?
I think questions purely about probability distributions with no reasonably obvious link to OR should be closed as off-topic and/or moved to the Stats or Math Stackexchange.
Questions with a link to OR (e.g. inventory theory, part of a model, simulation, modeling, ...) can be on-topic, if they require OR expertise to answer. A pure-stats question which just happened to appear while working on a OR related problem should be moved to the stats/math stackexchange.
Of course there are questions that could meet the requirements for both stackexchanges. In such a case I would expect the OP to search the stats/math exchange before asking on the OR exchange.
I mostly agree with Michael, but I think this will be a tricky line. E.g., I would like to see the one about loss functions considered on topic; it seems sufficiently related to inventory theory.
Also to Discrete lizard's comment, I think in enforcing whatever general policy we land on for math-related questions, we need to remember that folks have different definitions of what OR is and be a bit generous.
This is a good discussion to have -- I've upvoted the question despite one of the linked questions being mine. I agree with @E.Tucker that this will be a tricky line given the breadth of OR.
I almost didn't post that Q/A but decided it decidedly fit for the following reasons (of course, the community may disagree). OR is about supporting decisions --- using data, models, etc, but at the end of the day it supports decision-making. It may be process improvement, but still decisions.
On the site so far, I've seen inventory and operations management questions. I've seen (& even hesitantly participated in) reference questions and "softer questions."
There are Optimization questions which clearly fit. However, Simulation is another pillar method of OR. I wrote my Q/A in the spirit that it was a modeling decision when conducting input modeling for a Simulation or another Stochastics Process model, which I feel is within the OR scope.
I'm a bit concerned over this answer's wording (edited after this answer posted) that questions with no "obvious link to Optimization and OR should be closed" may unintentionally imply to others that OR is about Optimization. That's partly true. But OR is much broader than that. For example, in the US Military, Simulation is used more than Optimization by OR practitioners based on multiple surveys.
Again, this is a good discussion to have. We need to think carefully about what is on-topic at a site for OR.