This page explains how Isabella W. Zai (USATT# 1157628)'s rating went from 1223 to 1230 at the Boston TTC Div.B event from 20 May 2019. 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.