Game against cheaters

As far as I am aware, the explanation is actually simple mathematics. If you have 2000 elo and lost 5 points to a cheater, and now win as 1995 player 5 points - those 5 points are more then what you would have earned if you havn't played against a cheater in the first place (and had 2000 rating. Since the higher your rating, the lower amount of point you earn per win). So when the refund happens, it calculates those games that happen after the refund, as if you never lost to the cheater - those your overall gain is smaller then what you expected.

ok thanks

th2j is right, it doesn't make any sense that points don't get fully refunded. when someone plays a cheater, their rating goes below their actual skill level - so next time they play against an honest opponent, their opponent's expected rating change during that game is negative! (under normal circumstances, expected rating change should always be zero). so in effect cheaters make the whole pool lose rating constantly unless ratings get refunded!

@sahkal

Ok, but what about the new players who get rated 1500 and feed their rating to legitimate 1500s? I'd argue there are more new players than cheaters thus the rating gets inflated over time...

I think that's true and the only good reason i've heard not to do a full-scale rating refund

New players, or, in general, provisional players, do not feed their rating to anyone. They, more or less, have no rating.

When an established 1500 beats a provisional 1500? rated beginner, the gain in rating is lower as they would get by beating someone established from their rating range.
The provisional 1500? rated beginner loses over 200 points in that one game (please do not nail me on exact math) and gets paired with an established 1300 rated player who gains not much points as well and so on until the rating settles for the new player.

Needless to say that players on a new account might be pretty strong - and make their way up taking those few points from an established 1500 rated player.

You can read more about it under:
https://lichess.org/faq#provisional
https://lichess.org/page/rating-systems

@Funkmaus said in #5:

Clear "NO".
If we would "over-refund" you, we will just inflate your ratings.
Imagine you are losing to 3 cheaters during a long playing day, while fully recovering your points.
Then, you find yourself having a "non-earned" peak rating in a certain category just because we added points to your rating.
That peak will be an unreachable high, you will never be able to get there, it might hurt.
Another thing is that the rating you have is just a tool that is used to be paired with the opponents of similar skill level.
Believe me, if you magically get 100 points of the rating over night, all you have in return is pretty frustrating playing experience since players in higher rating range will just beat you down next day.
Are you still sure that you want that?
This is just a simple example why refunding over the rating you had before the game is simply wrong.
Thats a really bizzare take. If the guy got his rating points stolen by a cheater then the minimum lichess can do is to fully refund the rating points back. That he won some games in the mean time is irrelevant. It's not his fault the cheater didn't get caught sooner. I say lichess give this man his rating points back.

You're misrepresenting the point though. Nobody in this thread has said there shouldn't be a full refund. The complication is that you get points back by playing games, even if you lose them (because you lose less rating than if you hadn't lost them to the cheater- if I'm rated 1990 and lose to a 2050, I lose less rating than a 2000 would). So if you play enough games and then Lichess gives you a "full refund", you're actually getting 2 full refunds.

The other thing I just thought of is that giving this double refund actually incentivises people to wait before reporting cheaters. That doesn't help anyone.

The difference between a 1990 or a 2000 losing to a 2050 is minimal, probably 1 rating point at most.

Probably less than that, yes. But it adds up. So once you've played 20 or 30 games the result of the game against the cheater is barely significant at all. So why give them another (say) 10 points as OP suggests?