Nifty Labs, the marketing research group within Nifty Corporation, has developed filtering technology to automate the detection of so-called "Spam Blogs" - blogs whose sole purpose is to artificially inflate traffic and affiliate commissions. Japan has been renowned for the number such sites, and it is certainly an issue when trying to gauge the true blogging population and activity level here.
The survey combined several filtering techniques, and data came from a 100,000 article sample from 5 months of Nifty's Buzz Pulse Blog analysis service. Nifty says Buzz Pulse indexes 90% of Japan's blogs, including over 450 million articles as of March 2008. The average level of Spam Blogging was about 40% ...
Nifty plans to make this information available
on their BuzzSeeQer site - the online servce for BuzzPulse.
Press Release: http://www.nifty.co.jp/cs/07shimo/detail/080326003337/1.htm (Japanese)
Original Blog: http://bb.watch.impress.co.jp/cda/news/21375.html (Japanese)