Vietnam's students perform mysteriously well on tests, and a new paper has figured out why

Vietnam is one of education's biggest outliers: It's basically the only low-income country that performs at the same level as rich countries on international academic tests.

There's a clear positive relationship between a country's economic strength and how well its students perform on certain tests.

But Vietnam, with a GDP per capita that is a fraction of the US's, actually performs significantly better than you'd expect for a country at its level of income, and no one really knows why.

There are two internationally comparable tests that researchers have studied in an attempt to understand the mysterious "Vietnam effect." One is the TIMMS test, on which Vietnam vastly outperforms other countries of similar GDP per capita. Check out the chart:

A paper by Abhijeet Singh a few years ago studied the TIMMS results, and found that Vietnam's advantage starts early - Vietnamese children are slightly outperforming those in other developing countries even by age five, and the gap grows each year.

The paper finds that "a year of primary school in Vietnam is considerably more 'productive' in terms of skill acquisition than a year of schooling in Peru or India," Lee Crawfurd wrong in a blog post for the Research on Improving Systems of Education website. "The question this research raises - and the Vietnam experience suggests - is: 'Why is learning-productivity-per-year so much greater in some countries than others?' Or to put it more simply, why are schools so much better in some countries?"

Now, a new paper by World Bank researchers Suhas D. Parandekar and Elisabeth K. Sedmik is attempting to answer that question. They studied the Programme for International Student Assessment (PISA) exam, using scores from 2012.

There are only seven developing countries other than Vietnam that participate in the PISA, and at $4,098, Vietnam has the lowest per capita GDP out of all of them. And yet, Vietnam still scores higher than the other developing nations. Check out the chart for math scores versus per capita GDP:

Vietnam's scores are way above what you'd expect - more on par with Finland and Switzerland than Colombia or Peru. For math, there's a 128-point difference between Vietnam's score and the average score of the other seven low-income countries. Seventy points in the math section corresponds to "an entire proficiency" level, which represents about 2 years of schooling in the typical OECD country. Which means there's a nearly three-year difference in educational attainment between Vietnam and the other developing countries that took the PISA.

What's going on?

The World Bank researchers used the PISA data - which includes questions about student backgrounds, learning experiences, and school systems - to find out what about Vietnam makes its students so much better than its wealth would indicate. They found that investments in education and "cultural differences" can explain about half of the point difference.

A lot of the "cultural differences" had to do with student characteristics. In general, Vietnamese students were more focused and took their schoolwork more seriously. They were less likely to be late for school, had fewer unexcused absences, and skipped fewer classes. They spend about 3 more hours per week studying outside of school than students in other developing countries. They're less anxious about math, and more confident about how they're going to use it in the future.

There are more differences. Parents in Vietnam were more likely to be involved in their children's academic lives, and help out or fundraise at the school. Structurally, the education system is more centralized. Teachers are less autonomous - their performance is more monitored, and there's a higher emphasis on student achievement than in other developing nations.

But also - importantly - Vietnam seems to invest in education more than the other developing countries, especially considering its lower GDP. It has a lower level of economic development the other 7, the parents aren't as educated, and there are fewer schools in the cities and more in villages and small towns, all things that might not be particularly conducive to a good education system.

Despite the economic disadvantages, the quality of school infrastructure is better in Vietnam, as are the schools' educational resources. And even though there are fewer computers, they're just as likely to be connected to the Internet, which the researchers interpreted as evidence of Vietnam's increased investment in schools. There also seems to be more access to early education, as Vietnamese students were more likely to have attended preschool than others.

Of course, all these factors together only account for half of the achievement gap. The rest of the Vietnam phenomenon remains a mystery. But the results bode well for education and economic research, as we have a better idea of what can make a relatively poor nation perform just as well as a wealthy one.