Limitations of Google Analytics

Google Analytics is a useful tool for gathering information about who is visiting what areas of your site but there are some limitations to web analytics that you should understand.

Principal limitations

Accuracy

For many reasons, Google cannot track everything that happens on a web site so any numbers shown on reports should be treated as approximations.

Missing information

Many people will opt out of Google Analytics; they may also block cookies and/or switch off JavaScript which is how Google tracks the behaviour of visitors. Their activity is not tracked leading to under-reporting.

Unwanted information

There are two sources of unwanted information which will lead to over-reporting:

Internal traffic - by default data provided through GCC analytics includes traffic from internal users. This is not necessarily unwanted but if you are interested in the traffic to your pages by the general public, you will need to make arrangements to use the "External Traffic only" view.
Robots - while the method Google Analytics uses to track user activity will normally exclude most robot activity, it can't guarantee that robot visits will not pollute your reports.

Approximation

Because we use the free version of Google Analytics we do not get 100% of the traffic does track in every report. You can increase accuracy on some reports but this still does not use all traffic.

Some tracking needs setting up

Google Analytics automatically tracks standard web pages but not things like file downloads and clicks through to external links or to open email programs. These have to be set up and the code injected into the web page. (We use Google Tag Manager to do this but it's a specialist tool for which you need additional training.)