This page explains how Mark E. Berg (USATT# 6250)'s rating went from 1862 to 1813 at the Trolley Car TT Club Philly Ope held on - 30 Oct 2011. 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.