What does Sawmill measure?
Web Site Metrics
Sawmill can count web log traffic in several ways. Each way is counted independently of the others, and each has its own advantages in analyzing your traffic. The different types are:
Hits are events on your Web Site. It could be that a page was downloaded, or a PDF, or it could be just an image (one of many) downloaded on your front page. A single web page can be made up of many elements - it might have 10 images and a Flash movie (making 12 elements including the page). So if you had just one person visit only this one page, Sawmill would show 12 hits on your site. So if there are 5000 events for a single day, then Sawmill will report 5000 hits. Your Sawmill Administrator can help you remove traffic that you do not want to see in your reports.
Visitors correspond roughly to the total number of people who visited the site (see How Sawmill counts Visitors). If a single person visits the site and looks at 100 pages, that will count as 100 page views, but only one visitor. By default, Sawmill defines visitors to be "unique hosts" -- a hit is assumed to come from a different visitor if it comes from a different hostname (client IP). This is not the most accurate way of measuring visitors due to the effects of web caches and proxy servers. Some web servers can track visitors using cookies, and if your web logs contain this information, Sawmill can use it instead of hostnames (contact your Sawmill Administrator for more information). It is also possible for Sawmill to use WebNibbler™ Visitor Tracking, contact your Sawmill Administrator, or see The Sawmill Web Site for details.
Bandwidth is the total number of bytes transferred. Bandwidth is tracked for every event that occurs, whether it is a "hit" or a "page view".
Referrers are "where visitors came from". For instance, if a visitor first does a search on Google and then clicks on your entry in the search results then, when that visitor arrives at your site, the referrer is Google for that session and Sawmill will report Google as the referring web site in the Referrers view. For more detail, see Where did my visitors come from?
Several of Sawmill's reports deal with "session" information, including the The Session Overview and the "paths (clickstreams)" report. Sessions are similar to visitors, except that they can "time out." When a visitor visits the site, and then leaves, and comes back later, it will count as two sessions, even though it's only one visitor. The timeout interval can be changed, contact your Sawmill Administrator.