Be the kind of fish that needs a bicycle

Absolutes are the sworn enemy of web analytics and as time goes on, the weakness of web analytics can easily be exploited by the power of absolutes.  Embracing change and the nuances of behaviour should be part of web analytics.  This is the reason that pure numbers should be escewed in favour of trends.

For example, if 1000 people visit your website on the last Monday in February, should you spend $75 on a new banner ad for your sister site?  (If you said yes, you will make angels weep)

Absolute numbers and concrete definitions increase the chances of mis-reading and mis-understanding the data you collect on your website.
Assuming that a click on an exit link is the same as an indication that someone left your site will not take into account instances of mis-clicking and non-pursuance of the click.
Assuming that an exit page is the last page a visitor reads misses out on the fact that tabbed browsing may mean that the last page opened is insignificant to the visitor and the last page visited has been lovingly kept open on another tab.
Assuming that abandonment from a sales funnel is always a bad thing disregards the fact that you will learn more from those who abandon than those who obediently follow the path you have set to an ultimate goal.

Assuming that web analytics is only about online marketing is also a strange notion, to my mind.

Metric definitions can be a great way to communicate with others as part of the web analytics language, but it’s not the only way to communicate.  Analysts tend to have to report to non-analysts, so why speak web analytics to someone who speaks a different language?  The instances of overlapping terms could simply cause further confusion.

Pure numbers and restrictive definitions are a great way to learn and understand web analytics, but to develop and evolve, these need to be consigned to the toybox, only to be taken out from time to time.  Interpretation is the language of love in web analytics.  It is also the language of evolution.