This page explains how Qi Guo (USATT# 80876)'s rating went from 1847 to 1823 at the 2009 JOOLA N. American Teams O held on - 29 Nov 2009. 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.