We already knew that the “great firewall” barred many people in China from reaching websites deemed subversive or otherwise inappropriate by the government. Now comes evidence of just how sophisticated and widespread the censorship is even on sites inside the firewall.

Researchers at Carnegie Mellon analyzed how often posts to social networking sites in China will be deleted if they contain certain terms and found that, for example, at least 16 percent of the messages at one popular microblog site, Sina Weibo, were sent to the memory hole. The researchers document their work in great detail at http://www.uic.edu/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/3943/3169