I recently had a discussion with a coworker about a current promotion.  There was much concern that the promotion would drive traffic away from the page that otherwise might have stayed and followed its call to action.  The most reasonable approach was to watch the fall-out rate of the pages original call to action.

But then he posed an entirely different question.  How many visitors that followed the promotion came back around to the original page?  Herein lies the difficulty - there is only one segment of these returning visitors that we can measure - those who immediately return via their brower's back button.  A simple path report for paths containing the original>promotion>original page pattern.  This is what is called the bounce-back rate.  It helps answer the question, "Does the visitor see what they expected from the promotion?"

Now back to the difficulty.   Here are some other segments of the returning visitors that I came up with:

• Visitors who open the promotion in a new tab or window and later return to the originating page.
• Visitors whose visit ends before returning later.
• Visitors who navigate beyond the promotion page and return sometime later in the same visit.

I can imagine there being a way to track the last two by assigning a unique ID to every visit, then counting the number of unique IDs that visit the promotion page at least once and the originating page one more time.  A method like this would also include the back button segment.  However, it seems that the first segment is impossible to track.

This proves, once again, that web analytics is not an exact science.