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marketing-tech:google-analytics:setvar-and-the-zero-bounce-rate-bug [Jul 6, 2026 08:40 AM]
197.0.99.151 removed 		— (current)
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-= _setVar() and the zero bounce rate bug in Google Analytics = 
- 
-** UPDATE - Jan 27, 2009: Google has reportedly fixed the bug in GA that was causing the problem described on this page. Thus the fix is no longer necessary, but I will leave it here for historical reference. ** 
- 
-Google Analytics has a ''_setVar()'' function that lets you assign a single user-defined variable to be passed to your reports, which you can then see (and filter on).  
- 
-Unfortunately, using ''_setVar()'' on each page seems to break the bounce rate calculation in GA. This is because ''_setVar()'' apparently records a second pageview when it is called, meaning a visitor who left after their first pageview didn't actually 'leave' in the eyes of GA because they had a second page view secretly recorded via ''_setVar()''. Thus the bounce rate in Google Analytics drops to zero (or near zero) because //every single visitor// is getting hit with two pageviews.  
- 
-Conveniently, the value that you assign to ''_setVar()'' is stored by GA in the ''_utmv'' cookie, and the tracking code actually reads this cookie and passes back the value to Google Analytics, which records it for //every single pageview//, regardless of whether you set it with ''_setVar()'' on that particular pageview. Therefore **you don't need to call ''_setVar()'' unless you actually want to //change// the user defined value**. In fact, you //shouldn't// call it any more often than you have to, because you don't want to be creating these extra pageviews.  
- 
-This lends itself to a nice solution to the problem: we'll simply check if the value we want to call ''_setVar()'' with is already in the ''_utmv'' cookie. If it is, we'll skip calling ''_setVar()''. 
- 
-<code javascript> 
-/* 
- * getCookie(): given a cookie name, get its value. Returns null if the cookie can't be found. 
- * From http://www.webreference.com/js/column8/functions.html 
- * 
- */ 
-function getCookie(name) { 
-  var dc = document.cookie; 
-  var prefix = name + "="; 
-  var begin = dc.indexOf("; " + prefix); 
-  if (begin == -1) { 
-    begin = dc.indexOf(prefix); 
-    if (begin != 0) return null; 
-  } else 
-    begin += 2; 
-  var end = document.cookie.indexOf(";", begin); 
-  if (end == -1) 
-    end = dc.length; 
-  return unescape(dc.substring(begin + prefix.length, end)); 
-} 
- 
-/* 
- * utmvCookieCheck(): given a value, read the __utmv cookie and see if 
- * that value is already set. Return true if so, false otherwise. 
- * 
- */ 
-function utmvCookieCheck(value) { 
- var utmvCookie = getCookie("__utmv");  
-  
- if (utmvCookie == null) 
- return false; 
-  
- // get rid of the Google's domain prefix ID, which appear on all 
- // GA cookies 
- utmvCookie = utmvCookie.replace(/^\d*\./, ''); 
- 
- return (utmvCookie == value) ? true : false; 
-} 
- 
-</code> 
- 
-Now, just wrap your call to ''_setVar()'' with a call to check if the cookie exists first: 
- 
-<code javascript> 
-<script type="text/javascript"> 
-var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); 
-document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); 
-</script> 
-<script type="text/javascript"> 
-var pageTracker = _gat._getTracker("UA-XXXXXX-X"); 
-var userDefinedValue = 'CHANGE_ME_TO_YOUR_DESIRED_VALUE_FOR_SETVAR'; 
-if(!utmvCookieCheck(userDefinedValue)) { 
- pageTracker._setVar(userDefinedValue); 
-} 
-pageTracker._trackPageview(); 
-</script> 
-</code> 
- 
-That's it. Now ''_setVar()'' will only be called if the value isn't already set. 
-