Website Metrics

The language of Site Metrics is by no means uniform. Hits are often confused with uniques, and pageviews are often confused with impressions. So let's take a moment to clear things up a bit.

Hits

This term doesn't belong in your vocabulary unless you are a server administrator. Hits have nothing to do with traffic analysis. A hit is a request made on a server for a file. If you have dozens of small banners on each page, one pageview could result in dozens on hits. For purposes of measuring traffic, hits should be forgotten.

Files

Files are pretty much in the same boat as hits.

Files represent the total number of hits (requests) that actually resulted in something being sent back to the user. Not all hits will send data, such as 404-Not Found requests and requests for pages that are already in the browsers cache.
- Webalizer

Like hits, files are worthless as a traffic metric.

Impressions

Impressions is an advertising term. An impression has been defined by the advertising industry as a single showing of the creative. Impressions are counted in thousands. Pageviews are not impressions. To illustrate: I could easily have an impression inventory of 5,000,000 with only 1,000,000 pageviews if I'm serving five small banners per page.

Some people think that the Internet gave birth to the terms impression, and CPM, which is short for cost per thousand impressions. They are wrong. The advertising industry has been using these terms to refer to gross audience years before the Internet was even a twinkle in Al Gore's eye.

Sites

Sites are often confused with unique visitors. A site is simply a unique IP address making a request on the server. One unique visit from an AOL user on proxy IP can register as several unique IP's.

Search engine spiders can also artificially inflate the site count. This number should be ignored when quoting site metrics.

Pageviews

Pageviews can be a valid metric when assessing how targeted your traffic is, or isn't. Pageviews should be looked at in relation to visits and unique visits. A high pageview count in and of itself is not a sign of success, and is vulnerable to artificial inflation. In one instance I know of, a webmaster broke up his content into small pieces. An article that could be on one page was spread out across 10 pages in order to force a higher pageview count. For this reason, any mention of pageviews should be accompanied by a mention of unique visits.

Visits and Unique Visits

Visit
A Visit occurs when some remote site makes a request for a page on your server for the first time. As long as the same site keeps making requests within a given timeout period, they will all be considered part of the same Visit. If the site makes a request to your server, and the length of time since the last request is greater than the specified timeout period (default is 30 minutes), a new Visit is started and counted, and the sequence repeats. Since only pages will trigger a visit, remotes sites that link to graphic and other non- page URLs will not be counted in the visit totals, reducing the number of false visits.
- Webalizer

User Session
A visit is also referred to as a user session.

Unique Visit
A Unique Visit is the most important metric when assessing a website's reach. Considered together, Unique Visits and Visits, or User Sessions tell the story of a website's success or failure.

Sample Publisher Statement
As a publisher, when asked by an advertiser for your site metrics, a proper format would be:

We are currently conducting a monthly average of 156,500 user sessions for 97,300 unique users, with 2.33 pageviews per visit.

By stating uniques, user sessions and pageviews, you are giving the advertiser the information he needs to know in order to assess your reach, user retention and relevancy of the traffic to content.

This article by John Scott, a leading Internet marketing writer and consultant, and owner of V7N Internet Marketing Resource.