Conoce la terminología básica para entender los resultados estadísticos que te entrega tu servidor o servicio de estadísticas:

Visit - these are all requests made by a specific user to the site during a set period of time. The visit is ended if a set period of time (say 30 minutes) goes by with no further accesses. Users are identified by cookies, username or hostnames/IP addresses.

Hit - this is a request to the server for a file not a page. Your page can be made up of different files, such as graphic files, audio files or CSS and javascript files, resulting in a number of hits for that page. Each of these requests is called a hit.

Counting hits is not the same as tracking page views. It takes multiple hits to view a page.

Pageview/Impression - this is the number of times a page is accessed as a whole.

Unique View - A page view by a unique person within a 24 hour period.

Referrer - A page that links to your site. Looking at your referrers will tell you who’s linked to your site. This can be particularly valuable for seeing where your search engine traffic is coming from.

User Agent - This refers to the software used to access your site. Sometimes known as a "browser" or "client", the term user agent can describe a PHP script, a browser like Internet Explorer, or a search engine spider like GoogleBot. If you can identify what software is being used to access your site, you’ll be able to tell if users are abusing it, and when the search engines last crawled your pages.

Más Información en:
http://www.fortix.com.au/statistics-explanation-service.php
http://support.braschconsulting.com/statsinfo/statsinfo.htm
http://www.webmarketingnow.com/tips/weblogs.html
http://www.ask-susan.com/ask-susan-tips/April2003-HitsVsVisits.htm