According to the report, Behaviors of the Blogosphere (PDF file), from comScore Networks, almost 50 million--or one in six--Americans spent at least some time on blogs during that time frame. That's a 45 percent rise over the year before.
While there have been a number of studies about blog usage before, it has always been hard to statistically quantify how people use the online sites. And it's time that changed, said a researcher involved with the study.
"I see blogs as an important emerging piece of the media landscape," said Rick Bruner, who helped get the comScore study off the ground but who is now with DoubleClick. "But they're not well understood yet."
Bruner said data from comScore's study is likely to be more accurate than any before because of the methodology behind it. He explained that around 1.5 million Internet users allow comScore to electronically monitor their online behavior and that the sample size available for analyzing behavior is thus unprecedented.
"By comparison, the world of television media research is in the realm of a few thousand" people, Bruner said. "I had the confidence as a media research professional that (comScore) would have the ability to look at these relatively small sites with statistical" accuracy.
As part of the study, comScore came up with a list of what it calls the 400 largest blog domains. That includes around 370 individual blogs and about 30 blog hosting domains.
Other key findings from the study include the fact that five different blog hosting services--such as Google-owned Blogspot and LiveJournal--had at least 5 million unique visitors during the first quarter of 2005. Four different individual blogs had at least a million visitors.
For some time, sites like have attemped to maintain running measurements of top blogs and how they're used. But since everyone's methodology is different, results often vary widely depending on who's doing the measuring. With that in mind, the comScore study impresses some as being well in line with previously gathered data.
"Their list of top blogs correlates pretty closely with ours," said Kevin Marks, a principal engineer at Technorati. He said that's noteworthy because Technorati measures links between blogs, while comScore studied readership. "What it says to me is that the links do follow the readership."
Another piece of data in the comScore study worth noting is that blog users appear to come from wealthier households than other Internet users. And given the stereotype of blog fans, that comes as a surprise, Bruner said.
"There's this perception that bloggers are just college students or unemployed people," he said. "But a lot more Americans are seeing some value in blogs as a source of news you wouldn't necessarily see from the mainstream media."
For his part, Marks was surprised to see data showing that blog readers also visit almost twice as many Web sites as average Internet users and are more likely to buy things online.
"People are being engaged by blogs and doing more Web reading by following the links from the blogs," Marks said. "Once they discover Web logs as a thing to read, it also becomes a discovery tool. That's something we believe, but it's nice to have some confirmation of that."