Computer Scientists Measure the Speed of Censorship On China’s Twitter

The Chinese version of Twitter is a microblogging service called Weibo which launched in 2010. Dan Wallach at Rice University in Houston, Texas, and a few pals reveal the results of a detailed study of censorship on Weibo.

Their method has allowed them to reconstruct the censorship techniques used by the government, to calculate the number of workers who must be involved and even to discover their daily work schedules. Wallach and co say their data point to a number hypotheses about what’s going on. Since the highest volume of deletions occur within 5-10 minutes of posting, Weibo must be censoring them in near real time. If an average censor can scan around 50 posts a minute, that would require some 1400 censors at any instant to handle the 70,000 posts pouring in. And if they work 8 hour shifts, that’s a total of 4200 censors on the payroll each day. Even then, this work force must have some technological help. Wallach and co say the data suggests Weibo has a number of techniques in operation. The first is keyword alerting. When a keyword appears, the post is immediately flagged for censors.