As I understand it (an interested person like you all, not an expert or someone with the code)…
… the calibration is simply a formula to get from the rating to the rank.
You can think of it as X here: Rank = X divided by Rating
So simplistically we know that 13k = X divided by 1500
so X is about 1500/13 = 115.
It’s not that simple, but that is the idea.
The calibration was done for overall by first:
The trick is that you can’t properly compare numbers from a different pool of games. What this means is that:
If we applied the calibration blindly, I might turn out to be 10k live 9x9 and 12 k overall, but actually be worse at live 9x9.
Once again, my understanding (not authoritative) is that the Devs didn’t want this kind of comparison accidentally being made. They don’t want someone saying “I’m 1 dan live 9x9” because they know that this doesn’t mean anything other than you are a better live 9x9 player than an OGS 1k live 9x9 person.
I believe that they fear the risk that OGS would have Dan 13x13 blitz players, drawing ridicule because that is not a valid concept, and could result in people having airs and graces that they don’t “deserve”.
I believe they made the number table because the data is available and it is interesting for each of us to be able to know how our performance in the sub-types goes over time.
This statement back’s up @Ptro 's assertion that there shouldn’t be a table, there should just be separate graphs available for each sub-type.
I can’t think of any reason why the sub-type ratings should not be used for game matching. It seems like doing so would improve skill match in games…
GaJ