As the Big Data Expo, which hosted guests from senior Chinese government officials to chief executives of high-tech companies, concluded on Sunday, the city is trying to establish itself as a model for big data development.

Tang Hui, an official responsible for drink-driving tests at Guiyang Public Security Bureau (GPSB), said cloud computing makes data more secure. "The moment the breath test begins, the results are uploaded in real time via 3G networks to the system."

In the past, the test results were tampered with in some cases, said Tang.

Now, it is impossible to switch samples as all law enforcement personnel wear body cameras that record obstruction, said policeman Wang Yan.

The big data program also subjects all major police work to public scrutiny, thus, reducing the chance for rent-seeking and malpractice.

The GPSB said with the help of the system over the past year, dozens of police and mid-level officers have been called in for questioning. Another four resigned.