This page explains how Mac T. Horn (USATT# 6791)'s rating went from 1580 to 1530 at the 2012 U.S. Nationals held on - 22 Dec 2012. 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.