CourseDiff : a system for identifying and reporting changes to course websites

Abstract

CourseDiff is a prototype system that periodically samples course websites and notifies users via email when it identifies changes to those sites. The system was developed after conducting a study of 120 web pages from 50 MIT course websites sampled for two months during the spring semester of 2009. The study found that only 18% of changes to the HTML content of course website data are actually important to the content of the page. A closer examination of the corpus identified two major sources of trivial changes. The first is automatically generated content that changes on every visit to the page. The second is formatting and whitespace changes that do not affect the page's textual content. Together, these two sources produce over 99% of the trivial changes. CourseDiff implements an algorithm to filter out these trivial changes from the webpages it samples and a change reporting format for the changes that are identified as important. A small user test on part of the CourseDiff interface indicated that the system could feasibly be used by students to track changes to course websites.