Estimate, MSE, R2, MAD, MAPE, BIAS

https://habr.com/ru/post/19657/

https://ru.wikipedia.org/wiki/%D0%9A%D0%BE%D1%8D%D1%84%D1%84%D0%B8%D1%86%D0%B8%D0%B5%D0%BD%D1%82_%D0%B4%D0%B5%D1%82%D0%B5%D1%80%D0%BC%D0%B8%D0%BD%D0%B0%D1%86%D0%B8%D0%B8

https://math.semestr.ru/corel/prim2.php

https://en.wikipedia.org/wiki/Mean_squared_error