This page explains how Thong Nguyen (USATT# 75212)'s rating went from 1939 to 1940 at the 2009 San Diego Open held on - 26 Apr 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.