The Web site Apple.com attracted nearly 16 million American visitors last month. Some of them got there by typing in the address directly; others used a search engine, linking to company’s site via nearly 25,000 different keywords, including “iTunes,” “iPod” and “iPhone.”

So says Compete, a company based in Boston that tracks Net traffic. How does it know? It has installed its software in the computers of 100,000 Americans — with their permission — allowing the company to track their every movement on the Web. It gets additional, anonymous input on about 2 million American Web users from World Wide Web service providers.

That is a lot of society, but a far cry from the total U.S. Net population — more than 200 million, according to some estimates. Like other monitors of Web traffic, including Nielsen Online, Hitwise and ComScore, Compete extrapolates total Web audience figures from such samples, in a system similar to the panel-based research that is

used to measure television audiences.

Marketers rely on these numbers considering they are skeptical about notes submitted by individual Web publishers, which often seem to overstate their own audiences, at least by comparison with independent measures.

So, for all the talk of the Net being the most measurable, accountable, transparent medium ever invented, it can still be a frustrating place for marketers who just want to know precisely how many citizens will see their ads.

Advertisers have been pushing Net companies to produce more comprehensive, standardized info. But for now, in the absence of breadth, they are hungry for greater depth.

That is why Taylor Nelson Sofres, a market research company, said last week that it had spent $75 million, with as much as another $75 million still to come, to acquire Compete.

“We are listening to our clients, who have been telling us they want more and…

Orginal post by Top Tech News