Google Analytics Accuracy vs. Server Log Files Data

Google Analytics accuracy is not infallible. There are multiple issues that impact its accuracy, including the software platform it’s operating from. That would not be a problem if the average website owner/user actually understood the real purpose of Google Analytics.

Analytics is NOT designed to record website traffic statistics accurately. Google Analytics is less accurate, especially when compared directly against server log files.  GA is instead designed and intended to monitor and analyse what people do when on the site. That’s why it’s called “Google Analytics” and not “Google Statistics”…

Variations between Google Analytics and web server log files can vary from 10% to as much as 75%… That variation depends on the site architecture, any conflicting JavaScript code and sundry other variables!

GA results are indicative rather than absolute and are best used to identify trends, assess poor-performing pages, monitor the effectiveness of Adwords advertising campaigns and track visitor behaviour on the site. An SEO marketing company should be strictly honest with customers. GA should never be seen as an accurate way to measure website traffic. That’s NOT what it’s designed for. Despite that, there is endless discussion on this topic across the globe…

A client asked me this question a while ago;

Why are you ambivalent about Google Analytics?  Surely if one uses that consistently it is a constant so even if it is not 100% accurate the information it provides is relative.

My unsympathetic answer was;

Trying to use Google Analytics to assess web site traffic is like using a screwdriver to undo a nut… And yes, you can keep doing it over and over again. However, the RESULT is ALWAYS going to be suboptimal!”

How to use Google Analytics to Track Visitor Activities

Google Analytics is designed to monitor;

  • What people do when they are on your website
  • The pages they landed on
  • Where do they go internally?
  • Which pages do they exit from?

GA is a behavioural tool… It’s good at measuring conversion ratios. What percentage of people follow the traffic flow “funnel” you’ve visualised? How many end up doing whatever it is you’d like them to do? Regardless of whether that’s making a purchase, filling in a contact form or joining a mailing list, you’d like to know if things are getting worse or better…

You can edit a page and monitor the impact on conversions… You can alter your Unique Selling Proposition, or Call to Action, and measure the impact…

The accuracy shortfall is because GA is running as a tack-on chunk of JavaScript code at the top or bottom of your pages. It then passes information to your Google account. It is therefore prone to both interference and error… Other JavaScript elements on the site, web server software and PHP coding may easily interfere with Google Analytics accuracy and performance…

Google Analytics Limitations


Many ad filtering programs and extensions (such as Firefox’s Adblock and NoScript) can block the GATC. This prevents some traffic and users from being tracked. It leads to holes in the collected data. Privacy networks like Tor will mask the user’s actual location and present inaccurate geographical data. Some users do not have Javascript-enabled/capable browsers or turn this feature off. However, these limitations are considered small, affecting only a small percentage of visits.

The largest potential impact on data accuracy comes from users deleting or blocking Google Analytics cookies. Without cookies being set, GA cannot collect data. Any individual web user can block or delete cookies, resulting in the data loss of those visits for GA users. Website owners can encourage users not to disable cookies. For example by making visitors more comfortable using the site through posting a privacy policy.

GA uses a page tagging technique to collect visitor information via a combination of JavaScript and cookies. It has limitations with websites browsed from mobile phones. This is due to the fact that only the latest phones are currently able to run JavaScript or set cookies (Smartphones and PDAs).

These limitations affect all on-site web analytics tools that collect on-site visitor data using page tags. That is, the small piece of code (usually JavaScript) that acts as a beacon to collect visitor data.

Another limitation of GA for large websites is the use of sampling in the generation of many of its reports to;

  1. Reduce the load on their servers
  2. Provide users with a relatively quick response to their queries,

GA limits reports to 200,000 randomly sampled visits at the profile level for its calculations. While margins of error are indicated for the visits metric, margins of error are not provided for any other metrics in the GA reports. For small segments of data, the margin of error can be very large.

Other Ways That Dilute Accuracy of Google Analytics Results

  • Many people also set their browsers to clear cookies on exit
  • Other JavaScript applications may interfere with Google Analytics results
  • Code may not be correctly implemented

How to Get Accurate Website Traffic Analysis

If you want to know the answers to the “how many” type of questions then you should look in the server log files using AwStats or Webalizer. These are installed on and accessible from, most hosting accounts…

Real traffic volumes are measured extremely accurately by the web server, and recorded in log files in (almost) all hosting accounts. To really see what’s happening, you need to look at the hosting account’s traffic analyser software. Usually either Webaliser or AwStats (or both).

Of the two, AwStats is best because it excludes visits from all known search engine spiders and indexing agents, giving a much more accurate picture. Webaliser figures are often 30% – 50% higher because of that distortion.

Website Statistics Summary

You want to know more than either Google Analytics or server log files can tell you on their own;

  1. You can implement  Google Analytics on your website, to track where people go. That requires the insertion of a small block of JavaScript code in the footer. Visitor information is then channelled from your website to your Google account.
  2. You can look at your hosting account’s website traffic statistics, to assess total visitors, where they came from, how long they stay etc.

To really understand what is happening, you need to use BOTH mechanisms… and your local SEO company consultant can help you understand the strengths and weaknesses of each.

Page last updated on Wednesday, October 11, 2023 by the author Ben Kemp

Comments are closed.