How can overall total ranking and overall ranking for live games be different (in this case)?

[shinuito]

@GreenAsJade

Their opponent has a 9x9 rating of 1500 but an overall rating of 1000.

Clearly the impact on the new person’s 9x9 rating - where they lost to a much higher rated person - is less than the impact to on their overall rating, where they lost to someone who was the same rating as them.

@GreenAsJade

Right?

But no, not if only the overall rating is being fed into the exact same rating functions. If opponents 9x9 isn’t used, then it doesn’t matter at all. When the player’s 9x9 rating and overall are the same, the deviations are the same, then the result of the update should be the same?

And this is the point that I quoted above twice, and now for the third time

@anoek

@flovo came up with the great idea of using your opponents overall rating when updating a sub-rating,

@GreenAsJade

Clearly the impact on the new person’s 9x9 rating - where they lost to a much higher rated person - is less than the impact to on their overall rating, where they lost to someone who was the same rating as them.

So why “clearly”, if you never actually care about the opponents subratings when updating your own subrating?

It does say

using your opponents overall rating when updating a sub-rating

right?

It doesn’t say

using your opponents sub-rating when updating a sub-rating

right?

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Let’s assume we have this setup as you said, and because it’s glicko2 there’s volatilities v1 and v2 for each player.

p1 overall	p1 9x9	p2 overall	p2 9x9
1000 ±d1	1000 ±d1	1000 ±d2	1500 ±d3

Now if you only ever use the function f to update the ratings in the following way

f(1000,d1,v1, 1000, d2, v2) which updates the overall rank using opponents overall rank and

f(1000,d1,v1, 1000, d2, v2) which updates the 9x9 rank again using opponents overall rank

why do you expect different results? Are we using some non-deterministic algorithm? Does it depend on what day and time the game finished?