I was going to post this as a comment in the PR calculation thread but it feels like it should be a separate topic.

How do you guys calculate your PR?

Like I understand the formula (I can look it up) for any given match, but I am curious to know how to calculate your personal PR. PR can fluctuate wildly from match to match based on how easy the dice were to play and how easy the games were.

So what's the standard methodology? How many matches? How many games? Weighted average of match PR? Some other metric? Load all matches into XG and let it figure it out for me (I wish they had a download all button)?

Ie. my last 10 matches on backgammongalaxy (length - PR)
I feel like PR should be a weighted average of these based on match length, but now that I type this I feel like I should eliminate any match below length 3 as I play significantly better without the cube according to this small sample.

ps. I know I'm super bad based on these PR scores, but we all start somewhere.

Averaging your PRs together would make more sense if you played the same length matches all the time. Or I suppose you could average your 5s and 3s separately. It's not really that important to parse out; since PR is total errors divided by decisions, it somewhat takes into account match length. So averaging everything is a good enough rough estimate. Though the 1-pointers are really a different breed. I agree you should eliminate any match under 3 points.
BMAB does some sort of weighting of matches based on how long, but I'm not sure exactly how. I'd say at your level it's just not crucial to have an exact number. Once you start consistently getting under 8, then it's something to pay attention to. The nice thing about having a high PR is how easily you can whittle it down!

I actually asked the BMAB guy and he explained how they get PR, regardless of match length, with each point of a match counting as 1 experience point:

Add all errors over the last 300 EP. Divide by the number of decisions. Multiply by 500 to get PR. I think you get the same effect by looking at the Results tab in your XG profile. PR from the Summary tab is slightly different because newer decisions have more weight than older ones.