A college in eastern China that uses big data to identify students in financial difficulty says it has paid out millions of yuan in "stealth subsidies" over the past 13 years.

The University of Science and Technology of China introduced a computer system in 2004 that records and analyzes spending in its campus canteens, and began using it to identify struggling students.

At first, the system simply calculated the average amount students spent in a month, but this was not scientific, according to Dong Yu, director of student affairs for the college in Hefei, Anhui province.

"We quickly realized there could be girls on a diet and students who return home to eat," he said, adding that technicians optimized the statistical approach in 2005.

Li Feng, an employee of the office, added: "Since then, we've been calculating data, such as how many meals a student eats and how much he or she spends on average, and we compare these data with the average for similar students."

For example, if a student eats 70 meals in a month, the system will compile the data for all those who had 70 meals that month and compare the student's spending against the average for that group. "If the amount is far lower than the average, we will suspect that student is in financial difficulty," he said.

The next step is to consult with class advisers, who will be asked for their opinion on the student's overall situation.

Those who make the list for a discretionary subsidy receive an email and have 160 yuan ($23.50) credited to their canteen card－which can also be used in other campus stores－for the month. The list is updated on a monthly basis.

According to figures from the student affairs office, the university has paid a subsidy 40,000 times since 2004, providing a total of 6 million yuan to needy students.

"Interestingly, we have found that the canteen expenditures of the credited students does not rise considerably, while their expenditures in campus fruit stores and bookstores will rise after they get the money," Li said.

Li said the subsidy is just one way the college supports poor students. Scholarships, subsidies and loans have been available since 1999.

"The stealth subsidies are aimed at helping students while protecting their privacy and dignity," he said.