Understanding Stockfish's evaluation

[programarivm]

👋 Hello there,

Do the following numbers still stand for the new evaluation function?

Range	Evaluation	Symbol
-0.26 to 0.26	The position is equal	=
0.27 to 0.7	White has a slight advantage	⩲
0.7 to 1.5	White has a moderate advantage	±
> 1.5	White has a decisive advantage	+ −
-0.27 to -0.7	Black has a slight advantage	⩱
-0.7 to -1.5	Black has a moderate advantage	∓
> -1.5	Black has a decisive advantage	− +

See chesslablab/php-chess#343

Thanks for the help,

[cj5716]

Stockfish's evaluation has been normalized, which means that a 1.0 evaluation stands for 50% chance of win.
I am not sure where you got those values, and whether they are accurate.
#4636 as you can see from here, ~0.5 is a 5% chance of winning, ~0.6 is a 10% chance of winning, ~0.8 is a 25% chance of winning, and so on.

[vondele]

Also https://github.com/official-stockfish/Stockfish/wiki/Stockfish-FAQ#interpretation-of-the-stockfish-evaluation

[programarivm]

Chess\UciEngine\Stockfish.php is now using the new evaluation function with the ranges described above. See StockfishTest.php.

[DrGrekenstein]

official-stockfish/Stockfish#4373

Before normalization internal units / 208 is value in pawns. Now instead it divides by NormalizeToPawnValue (initially 348, shortly after 361, and now 394)

So Stockfish's evaluation is unstable and It is not understandable.

[Sopel97]

No. It's perfectly understandable, because it has a clearly defined meaning now. It's even explained in the issue you linked.