Discussion on answer by Dale M: What should be done if I suspect a player is using weighted dice?

You make good points in this answer, but I'm not a fan of how you strongly assume the OP is wrong and doesn't know about confirmation bias. You claim you're "99.9% sure his dice are perfectly fine", but you have absolutely no basis for that claim, which comes across as a bit condescending.

@DaleM So you're applying your own bias of "people don't know about confirmation bias" to the situation ? You could simply warn OP about confirmation bias without telling them the dice are definitely fine, which you don't know.

@PierreCathé you mean apart from having taught statistics to post-graduates?

@AndrewSavinykh absolutely- people are more important than pure rationality. I’m an engineer and a scientist and I know rationally that dice are not “lucky” - that doesn’t mean that my emotions about dice and luck follow my rationality.

@AndrewSavinykh Sorry but if you accuse me of something without any proof besides getting some good rolls, and get everyone on the table to gang up on me, it sounds like you have already made up your mind. And in fact OP has made up their mind, they think the player is definitely cheating. The player should emphatically refuse being treated like they are guilty, and they should not only refuse to let people mess with their stuff, but they should probably not play with people who are so toxic.

+1 for the first half, -1 for the second. If you're going to ignore it/forget it there's no point in checking in the first place. That said, I value my time, and you should too. If someone is cheating they may not be losing you money, but they are cheapening the experience and possibly wasting your and your party's time. Further if someone is willing to cheat in a game with no stakes, there's no telling where else they're willing to cut corners.

Casinos have standards for dice quality that are ridiculously high by typical RPG player standards. Meeting those standards is meaningfully expensive to achieve, and dice that are that good will generally have it as a prominent selling point - and they still won't stay that good for long if they're rolled a lot. I would be surprised if there's even a single die "good enough that a casino would use" among the entire group of players.

You have abused statistics in a way that reminds me of the "on average, each human has 1 teste and 1 breast" joke. Weighted dice are a thing and people buy them. Some use them to cheat. It seems more likely that if they are weighted then the owner probably knows and bought them for that reason. It seems unreasonable to assume 0.1% odds of knowing. Your stated odds suggest less than 1 in 1000000 people cheat with weighted dice, a shocking assessment. Otherwise good/funny answer +1, especially the "more likely to be a murderer", but I suggest you improve your answer's statistical analysis.

Never assume to malice What can be attributed to random chance.

Absolutely agree with this answer. D20s "fixed" effectively enough to have any statistically significant deviation will either behave or look extremely obvious. They'll visibly roll very very weirdly due to weighting, magnetism or stickiness, or will have the high numbers visible in a cluster (ie, 18 and 19 next to 20, missing numbers, etc). Even reliably-weighted D6s roll funny, and they have a lot less work to do to act weighted! Realistic-looking weighted D20s that affect the outcome enough to be noticed, simply don't exist.