I think you’ll get there...

Look what I just saw!

Whaaaat!! You caught the unicorn :D

I am going to bet you get all the way to 10/10/10. I think current generation has access to more frequent training, more black belts able to promote, etc. that is going to move average from 12 down to 10 ish. At my gym promotions past blue are typically 2.5-3 years, and white to blue generally less than 2.

Question for Christian: do these averages include only black belts’ histories, or does each level include all the folks who got to that level? Ie the time to purple includes all purples and up.

I'm not sure I follow you 100% but the stats are just showing average time spent at each belt for verified profiles. So a purple belt will add to the numbers with his/her white, blue and purple time. White belts will chip in with time served from training started until today.

Oh so the average time at blue actually includes still-blue, etc.

Correct

So in some way, I should maybe have a "stopped training" date in the promotion history. Otherwise people who are not training, will keep adding time to their belt rank's stats until they die :D For now, I presume that anyone on here are actually training.

For now that's probably a safe assumption--I can't imagine too many people have quit training, but created beltchecker profiles this month. However, in a couple of years when you have dormant accounts, yeah maybe filter them out of the time at rank stats.

Right now though, what's interesting is the stat doesn't quite mean what I thought. I was reading it as, 'how long on average did it take to go from white to blue, blue to purple, purple to brown, brown to black.' But in fact all of the yet-to-be-promoted folks are shortening the average (and I suppose the will-never-be-promoted folks are lengthening it. To your point, if you just let it run, the average time spent at white belt could get to 40+ years.)

For the black belt one, are you summing the times from the lower levels, or calculating start date to black belt date from black belt profiles only? I think the latter is the cleaner way to do it.

I would be very curious to see trends along these lines:

average time to black belt [black belt reached 2015-2029 | black belt reached 2010-2014 | reached 2005-2009 | reached 2000-2004 | reached 1995-1999 | reached before 1990-1994 | OGs]