Known as the Twitter of China, Sina Weibo is also infamous in the West for the number of high profile users who have had tweets censored, including Kai-fu Lee. The former head of Google China, who was once booted off Sina and Tencent Weibo for three days, recently made a graph of how often his microblogging posts have been censored.
Computer scientists Jed Crandall and Dan Wallach conducted a study on how quickly censorship on Sina Weibo can work, with findings reported by the BBC and originally published on arXiv.org. The two researchers, who believe their study is the first “real-time analysis of Weibo posts,” say they “found a landscape in which a post could be deleted as quickly as five minutes after being put online and where the censors appear not to work a regular day, but seem to take a break when China’s all-important 19:00 news comes on.”
Censors work rapidly: most deletions happened within the first hour after a post had been made, with about five percent of deletions happening within the first eight minutes, and 30 percent in the first half hour. Nearly 90 percent were made within the first 24 hours.
Crandall and Wallach spent 30 days tracking posts by 3,500 users on Sina Weibo. During that time, they write, 300 of the accounts, or 12 percent of the total, were deleted. Accounts that got censored the most often also had posts censored the most quickly, showing that they might be the target of more scrutiny.
Though they could not estimate the exact number of people dedicated to deleting posts on Sina Weibo, the two computer scientists said that Sina Weibo would need to employ at least 4,000 censors every day if none of the process was automated.
Crandall and Wallach called censorship a “sophisticated operation,” with “relatively sophisticated programmers who build their censorship tooling.” Automated systems appear to include keyword alerts for sensitive topics, as well as monitors for certain users who write frequently about controversial issues.
Launched in 2010, Sina Weibo has 300 million users, with about 100 million messages sent daily.