This is a pretty stunning idea considering the level of decision making within the online industry that currently happens based on the statistics that are displayed in Google Analytics.

After talking to a few others about this issue, it turns out there may well be a growing question surrounding the importance that Google Analytics has in the decision making process. There’s this case study completed by Michael Martinez on SEOMOZ which, while a few years old, asks some very pertinent questions. How often have you questioned your Google Analytics package?

Thinking back 5 or 6 years in the online industry (prior to Google entering the web analytics vertical through acquisition) webmasters would regularly question anyone who quoted page views or page hits as it was widely accepted that the stats were particularly varied and often inaccurate.

With a company like Google taking on the mantle of free web analytics and effectively taking over the free market with a sophisticated product, the question just doesn’t get asked as often as it used to be. Do too many online professionals blindly trust Google to give accurate data through what is an imperfect tracking medium?

There is an interesting article available by Brian Clifton who took two sites and compared their tracking between Google Analytics, Yahoo Web Analytics and Nielsen Site Census. Here was the basic conclusion of his findings;

The methodology of page tagging with JavaScript in order to collect visit data has now been well established over the past 8 years or so. Given a best practice deployment of Google Analytics, Nielsen SiteCensus or Yahoo Web Analytics, high level metrics remain comparable. That is, can be expected to lie between 10-20% of each other. This is surprisingly close given the plethora of accuracy assumptions that need to considered when comparing different web analytics tools.
As tracking becomes more detailed – for example the tracking of transactions, custom variables, events and outbound links, the greater the discrepancies of metrics will be between the web analytics tools.

General discussions with a couple of industry people has suggested using a product like AWStats as a test against the particular product you’re using (e.g. Google Analytics) to make sure you’re not missing a part of the bigger picture through the use of only a single analytics package.

Do you have any data on the subject?