Webtrends Analytics 9 Adminstration Guide, November 2012
If you compare Express Analysis report data with data from standard Webtrends Analytics 9 reports, you should expect some differences in results, even when you compare data for the same time period. These differences occur because Express Analysis uses different methods of data collection in order to provide fast results.
For example, standard Webtrends standard analysis identifies visitor sessions using the tracking methods specified in the Session Tracking settings, which can include cookies, authenticated user name, and other criteria. Express Analysis identifies the start of a visit by tracking a specific data tag which requires an enabled browser cookie. Thus, because Express Analysis can only track visits for visitors whose browsers accept cookies, visit counts tend to be lower in Express Analysis reports.
Express Analysis reports typically also include data from standard Webtrends analysis. For example, if you include reports that are not Express Analysis-compliant in your report template, Webtrends populates these reports with available data from standard analysis. Webtrends identifies reports and report elements based on Express Analysis by labeling them with the Express Analysis icon. The Express Analysis icon is displayed in the report Table of Contents next to each report that contains Express Analysis data. Within reports, the Express Analysis icon is displayed next to each report graph and table that is based on Express Analysis data.