This page explains how Jon Dorn (USATT# 37971)'s rating went from 1965 to 1964 at the 2009 US Nationals held on - 19 Dec 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.