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Understanding Website Statistics

Checking website statistics is part of the testing process. There are two types of data that can be collected: web logs and page tags. Web logs are the trace left behind by every call to a website from a browser, whereas page tags are a special marker code placed on a page which monitors the website use from the browser end. There are differences between these two types of report and in practise both are useful to have. However interpretation of the results requires some understanding of the terms.

Google Analytics

A widely used page tag type of system is Google Analytics which gives many statistics in depth. The interpretation of these figures can cause problems as they do not explicitly offer access to the underlying numbers, which are necessary to understand how a site or a page is really doing.

Underlying Numbers

The underlying numbers in which we are interested are of four kinds:

Knowing these figures would give us a clear idea of how the site is doing. In particular a useful figure would be the "II" number to show how many people have stayed on the site. However from the set of default statistics given this is not possible.

Pageviews, Bounce Rate and Exit Rate

Among the default statistics for All Visits to a website are: Pageviews, Bounce Rate and Exit Rate. These are made up from the underlying numbers like this:

Manipulating these figures will not allow us to find out what each of the underlying numbers is. To do this we have to use an option on Google Analytics which will show "Non-bounce Visits".

Finding Non-bounce Visits

At the top of the Google Analytics page is a heading called "Advanced Segments". It is on the right hand side for the old version of Google Analytics and on the left hand side for the new version. If you click on the down arrow it offers a section called "Default Segments" with a tick in the "All Visits" box in the old version, but blank in the new version. If you are using the new version then tick all "All Visits".

If you scroll down to the bottom of "Default Segments" you will see an option for "Non-bounce Visits". Tick this box, then press the "Apply" button on the screen. The dashboard will then show two lines on the graph and two sets of numbers for each of the types of visit.

What Non-bounce Visits Means

When you compare the numbers for Non-bounce Visits with All Visits you will see the following:

This enables us to work out that for Non-bounce Visits the statistics are constructed like this:

This breakdown allows us to calculate the underlying numbers and make more detailed judgements about the website. The method of calculation is shown on this page.