This page explains how Wei Qin (USATT# 215793)'s rating went from 847 to 838 at the ICC - Sunday Beginners League event from 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.