The new Google Analytics tracking code (ga.js) has been launched and is now available for you to use when you set up a profile. Installing the lighter ga.js code snippet instead of the old tracking code (urchin.js, “legacy”) lets you take advantage of upcoming advanced features and sophisticated reporting while keeping the reliable tracking capabilities of urchin.js. For these reasons, we recommend installing ga.js instead of urchin.js. For more information on the new ga.js code, including information on migrating over from “urchin.js,”

Link:
https://www.google.com/…/answer.py?answer=55488

Migration Guide:
http://www.google.com/analytics/GATCmigrationguide.pdf

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