There are every now and then discussions about where the Worldbuilders are active outside WB.SE. The definition of active is of course hard to define, but a user reaching a certain reputation usually indicates a certain activity (even if that activity could be quite old). In any case, I wrote a SEDE query:
It requires to set a minimum threshold. Find the list of all SE sites and compare on each site how many users have more than the given reputation threshold on both WB and the other sites from the list. Anyone can try it out.
But just to give some example, if we follow the standard of SE that requires 200 reputation to be considered active, we get the following overlap for WB:
Stack | User overlap ------------------------------------ StackOverflow | 53.3 % SFF | 26.4 % ELU | 23.0 % Programmers | 16.4 % SuperUser | 15.7 % The Workplace | 15.4 % RPG | 15.0 % Meta | 14.8 % Security | 12.8 % Gaming | 12.4 % Physics | 11.7 % Academia | 11.2 % Puzzling | 11.0 % Code Golf | 11.0 % Maths | 11.0 %
for the top 15 overlap.
If you are curious about who are the users present on two concrete sites, you can use that other query.
Please note that I am a total beginner in SQL, so don't be too harsh about non-optimum syntax.