How accurate are web site statistics?


Web site statistics are not 100% accurate. Technologies used at large Internet Service Providers (ISPs), like AOL, and many businesses affect the accuracy of web site statistics. Many people may appear to be one person or one person may appear as many people viewing your web site. Web site statistics cannot tell you exactly how many visitors are looking at your web site. Web site statistics should be used to measure growth in visitorship. You can use the numbers provided to calculate percentage of growth.

Brief scenarios illustrating why web site statistics are inaccurate are provided below.

One person appearing as many
There are a lot of people using computers at Jill's work. Jill's work, like many businesses, doesn't use modems to connect to the Internet. All of the computers are networked together and use a single fast connection to the Internet. The computer geeks at her work have chosen to use a technology which will assign Jill's computer a new IP address periodically. Jill's computer could be assigned a new IP address every night, or even while she's in the middle of surfing a web site. As I'm sure you can already see, when Jill's computer at work is assigned a new IP address, she will then appear as a different person. Jill's computer may be assigned a new IP address even while she's surfing your site. This means, in one visit to your site, Jill may appear as two people. This technology is also used by some ISPs, like AOL.

This same technology may also cause multiple people to appear as one person, as is described below.

Multiple people appearing as one person
With the same technology just described, the IP address that Jill's computer was assigned will be assigned to another computer at her work. Jill sent the address to your web site to a coworker, David. David's computer just happened to be assigned the IP address that Jill's computer had a moment ago. When David visits your web site, he will appear to be the same person as Jill. Jill and David will be seen as the same visitor in your web site statistics.

What is a Cache or Caching?
Caching is the process of storing information for easy retrieval later. Your browser cached this web page. If you go to another page, then click the back button on your browser, chances are the web page will come right up without redownloading it. Also, your ISP may cache information so that they themselves don't have to go out and retrieve information again from the Internet. This widely used technology makes all statistics inaccurate.

What is a Hit?
A hit is a request for a file. One web page consists of several files. This web page, at the time of this writing, contains 12 files. The first file is the HTML, then each image on the page is another file. Images that change when you put your cursor over them are actually two images.

What is a Page View?
A page view is each time a page is delivered. This term is often used when buying and selling advertising. You can use this statistic to tell potential advertisers how much advertising you can deliver. A page view is a collection of hits.

What is a Visit?
A visit is a visitor's visit to your site. One visitor often generates many visits. A visit is a collection of page views.

What are Members, Subscribers, Readership and Visitors?
All of these terms have slightly different meanings, and are often misused to describe a visit. Generally these terms are used to describe the number of unique visitors to your site.

What is are Unique Hosts or Unique Sites?
This is a statistic that is usually used as a substitute for the visitors statistic. Host is another name for a computer. This statistic describes how many unique computers visited the web site.