Serbia’s universities are the most effective in the world when countries’ levels of economic development are taken into account, according to a new ranking of national higher education systems.

The Balkan country has overtaken the UK to take pole position in the Universitas 21 development-adjusted ranking for 2017, up from second in last year’s table. The US is ranked 15th.

But Serbia is again ranked at just 39th place in the overall top 50 ranking, which is based on systems’ absolute performance. This table is topped by the US, followed by Switzerland, the UK and Denmark.

The Universitas 21 rankings are created by a global consortium of research universities to compare the performance of whole countries, as an alternative to other rankings that focus on individual institutions.

The rankings are based on 25 separate variables, including the number and impact of research articles produced, university enrolment and graduate unemployment, a qualitative assessment of a country’s policy environment, and spending on tertiary education as a proportion of GDP.

For the first time this year, the table also looks at the diversity of institutions in countries’ university systems.

Ross Williams, emeritus professor of econometrics at the University of Melbourne and lead author of the study, said the UK dropped one place in the development-adjusted ranking because its GDP per capita increased by 4 per cent between 2013 and 2014 – the years analysed in the 2016 and 2017 tables – while Serbia’s income per head had “barely moved”.

“This means that for the UK higher education sector to hold its ranking relative to Serbia it had to improve at a significantly higher rate than Serbia,” he said. “Relative to other countries at similar levels of GDP per capita, such as Thailand, Serbia’s research expenditure is high, as is its research output.”

He added that because the measures take population into account, the ranking “may favour small countries”.

Last year, Times Higher Education identified Serbia as one of seven nations collectively called “the TACTICS” that could grow into star players in global higher education, on account of its GDP per head, student enrolment numbers and growth, research publication output and growth, and field-weighted citation impact.

Elsewhere in the GDP-adjusted table, China has fallen from 5th to 14th owing to the growth in the country’s economy and methodological changes in purchasing power parity adjustments, while South Africa has climbed four places to third because it has “grown at a less than average rate in GDP per capita”, according to Professor Williams.

Universitas 21 ranking 2017 top 10: main ranking

Overall Rank in 2017 Country Rank in 2016 1 United States of America 1 2 Switzerland 2 3 United Kingdom 4 4 Denmark 3 5 Sweden 5 6 Singapore 8 7 Canada 9 8 Netherlands 7 9 Finland 6 10 Australia 10

Universitas 21 ranking 2017 top 10: adjusted for average incomes

GDP Adjusted Rank in 2017 Country Rank in 2016 1 Serbia 2 2 United Kingdom 1 3 South Africa 7 4 Denmark 3 5 Sweden 3 6 Finland 6 7 New Zealand 9 8 Portugal 8 9 Israel 11 10 Australia 14

ellie.bothwell@timeshighereducation.com