This page explains how Mark Johnson (USATT# 26863)'s rating went from 1870 to 1853 at the ICC Juniors and Adults League event from 6 Oct 2008. 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.