Why Google Analytics Gives Different Results
Posted Monday 21st September 2009 by Allison in Analytics.
Web Analytics
Web analytics services can differ greatly in their methods of tracking website traffic, and so there can be huge discrepancies in numbers reported by Google Analytics and other analytics service providers.
There is a myriad of variations in the ways various providers collect and collate their information. For example, should a provider group data according to different time zones, then this would probably affect its daily or hourly report data.
Due to these discrepancies, when using data to make decisions about analysing user behavior and search engine optimisation, it’s best to measure metrics thrown up in analytical reports in terms of percentages and trends, rather than hard number data, when making decisions about user behavior for search engine optimisation.
Google Analytics
One of the main differences in practice is the use of JavaScript/cookie-based tracking versus logfile tracking. Google Analytics utilises the JavaScript/cookie-based method, meaning pieces of JavaScript can be installed onto individual website pages, which are then executed, resulting in a cookie being placed on a visitor’s computer each time a page is visited.
This system is brilliant for uniquely identifying each visitor to a page. However, other analytics solutions utilise a log file/IP + user analysis, which parses IP and user agent data and logs it for a logfile, and these two different methods of gathering data can produce vastly different statistics.
JavaScript
Google’s JavaScript analysis can produce lowers results numbers than logfile analysis because it relies on cookies and images being enabled by a user’s web browser. If cookies are disabled, the analytic service will not count the visit, and so JavaScript analysis generally produces lower visitor numbers than logfile.
Some analytics providers use third-party cookies, which as the name suggests, are not set by the website being visited, and for this reason they are often blocked by web browsers and security software. The numbers reported by this method will be lower than by Google Analytics as Google only uses first-party cookies.
However, JavaScript execution means that Google’s servers are told directly each time a user visits a page, regardless if the user’s computer has locally cached the page. Other packages may not record pages pulled from a local cache when a user visits a page for a second time.
Analytics Solutions
Most analytics solutions allow users to tailor the way data is interpreted and offer options on the filtering of data. This can cause discrepancies in numbers between different package providers.
In a similar vein, analytics solutions terminology can vary in meaning, or data can be gathered in a different way, between packages, and this can cause the metrics in reports to vary. For example, Google Analytics provides a customisable-in-length session time in which to record visits to a site.
Other providers may have various session timeout periods and settings that differ greatly, from 30 minutes of site inactivity, to the exiting of a browser. Of course, different settings in the recording of frequency of visits will result in drastically different visitor hard numbers, but possibly similar trends within different analytics solutions.
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