This page explains how Zhaoqun Zhou (USATT# 4287)'s rating went from 1928 to 1931 at the Westchester 2021 September Open held on 25 Sep 2021 - 26 Sep 2021. The links below take you to pages that describe various aspects of the rating processor.

The rating processor goes through 4 passes in order. The links take you to pages that provide detailed explanations of the calculations during each of the 4 passes.