Google analytics event tracking (web tracking)

• is a method in ga.js
• record user-interaction with web element
• attach method call to paticular UI element
• pageview calculation unaffected

Setup:

• _trackEvent(category, action, opt_label, opt_value, opt_noninteraction)
• Ex: _gaq.push('_trackEvent','Videos','Download','Gone with wind');
• Category:
• required, appear in event report
• the group name of the objects we want to track
• Actions:
• In report actions are listed independently from parent category
• Unique event is affected by unique action name
• unique event per category-action pair
• difference in "top action" and "category action" report
• Labels:
• not required
• can provide additional dimension in report
• Values:
• not required, integer value, NOT negtive value
• Non-interaction events:
• If set this attribute to True, means this user-interaction does not counted as an interaction on this page. So if the visit ends from this page, the page is considered "bounce", even user did some action on this page. 
• By default, event tracking might decrease bounce, because element get interacted and trigger event, that's because event_tracking is the same as page tracking - an interaction request.
• Event tracking that automatically loads on page will result in zero bounce rate on that page.
• Event tracking has hits number limit, so should not do too many repetitive event tracking.