Here is a story from Salon about the problems of "web numbers".
<<Page views and unique visitors are valuable statistics, and auditing companies like I/Pro emerged to validate them, but they both have serious drawbacks. If you hook up to the Net by dialing a modem into a service provider, odds are good you are assigned a "dynamic IP number": The number changes each time you dial up, so you might show up as 30 different "unique visitors" to a site you visited daily for a month. And the practice of "caching," which different kinds of networks (most notably AOL) adopt to speed the delivery of Web pages, reduces the amount of traffic (both page views and IP numbers) the originating site can accurately count.
The new online medium had promised marketers and advertisers that it would offer them a wealth of detailed information about usage. But because of these complexities -- and because Web users resisted early experiments requiring site registration (HotWired was an important litmus test) -- it began to seem that the Web actually offered less reliable information about who saw what than even those dinosaurs, TV and radio.
So over the last two years a wave of new companies -- led by Media Metrix but also including its competitors Relevant Knowledge (which Media Metrix purchased last October) and NetRatings (now allied with Nielsen) -- set out to measure the Web the old-fashioned way, following the "Nielsen family" model. Each of these companies finds a random, statistically valid sampling of users, plants tracking software on their computers and follows them on their online travels. Then it extrapolates those usage patterns to get a full picture of Web use: If 40 percent of participants visit any page on a particular site during a month, then that site has a 40 percent reach.
salonmagazine.com
In itself, sampling is a proven approach -- ask any pollster. But it's alarming that the competing sampling services seem to come up with wildly differing rankings. And Media Metrix has problems building a reliable sample: To date, its Achilles' heel has been its troubles getting its tracking software installed on workplace computers. Many commercial Web sites see their highest traffic during work hours and believe that their users are visiting from their office desks; these sites feel they're being short-changed by reach numbers. And though Media Metrix says it's working hard to improve its workplace coverage, many businesses are reluctant to install the software -- possibly for technical reasons, possibly because they don't want to learn how many of their employees are sneaking peeks at Penthouse on the job. >> |
