[00:00.41]With more than half a billion Chinese online,
[00:03.14]and many of them avid microbloggers,
[00:05.32]the speed of censorship uncovered on Sina Weibo is astonishing.
[00:09.89]The researchers mined data on microblog comments removed by administrators,
[00:14.77]and found that nearly a third of the deleted posts
[00:18.90]were taken down in the first 30 minutes.
[00:20.71]Unsurprisingly, criticism of the government,
[00:23.20]local scandals and complaints about China's one-child policy
[00:26.89]were blocked most quickly.
[00:28.38]But the team worked out that if none of the process was automated,
[00:32.17]Sina Weibo would need to employ more than
[00:34.69]4,000 speed-reading censors a day, just to keep up.
[00:38.95]The researchers uncovered a range
[00:41.05]of devices aimed at bringing bloggers into line.
[00:43.79]They included, hiding posts from other users,
[00:46.49]flagging repeat offenders for closer scrutiny,
[00:49.57]and tracking backwards to delete sensitive topics everywhere they arose.
[00:54.11]With China's media so strictly controlled,
[00:57.03]the study has raised questions about
[00:59.42]why microblogs allow people to post before censorship at all.
[01:03.69]One of the researchers, Professor Dan Wallach,
[01:06.61]told the BBC that Sina Weibo had to satisfy government censorship requirements
[01:11.81]without seeming heavy-handed to its bloggers.
[01:14.56]He said it had to walk a fine line.
[01:17.11]