And probably one of the few ways to actually get valid surfing habits. Thanks for the clarification.
More on why Comscore's sampling is better than most other web tracking services:
http://www.comscore.com/metrix/xpc.asp
Superior Methodology Delivers Unparalleled Insight
Media Metrix 2.0 and Media Metrix XPC combine time-tested and innovative measurement approaches that include:
Foundation of pure Random Digit Dial (RDD) recruitment In keeping with comScore Media Metrix’ commitment to trusted media research methodologies, RDD – a methodology long endorsed by media researchers – continues to be at the heart of the Media Metrix 2.0 service.
Largest Work Sample – Accounting for nearly half of the U.S. online audience and 60 percent of online dollar sales, at-work Internet users are an increasingly critical population. Media Metrix 2.0 delivers the most accurate and comprehensive reporting of Internet behavior in the workplace using a sample of more than 100,000 panelists, many times larger than the size of any competing service.
University Measurement – The 9 million U.S. college and university students online represent an important and impressionable audience for marketers. Only Media Metrix 2.0 features a unique 40,000-member sample to provide exclusive data on this important audience.