World university rankings: explained

How the most widely cited global rankings are measured, and which institutions made their top tens for 2019.

  • Bec Crew

Credit: mauritius images GmbH/Alamy Stock Photo

World university rankings: explained

How the most widely cited global rankings are measured, and which institutions made their top tens for 2019.

22 August 2019

Bec Crew

mauritius images GmbH/Alamy Stock Photo

The Academic Ranking of World Universities (ARWU), which last week released its top universities for 2019, is just one of the multitude of ways in which higher education institutions are pitted against each other.

Among more than 20 different global ranking systems, the longest standing and most influential are the ARWU (produced by the ShanghaiRanking Consultancy), Times Higher Education (THE), and Quacquarelli Symonds (QS).

Whether it's about funding and endowment; research excellence and impact; student admissions and satisfaction; or graduate employment, international reputation and awards, there is a vast array of factors to compare, and even more ways to combine them into proprietary ranking algorithms.

Below is a breakdown of the most important components of each of the big three, and their top 10 institutions for 2019, along with a description of the Nature Index, for comparison.

The Academic Ranking of World Universities (ARWU)

Established in 2003, the ARWU was the earliest global university rankings system of its kind, using a combination of factors to compile its annual league tables.

Originally published by the Shanghai Jiao Tong University to identify the global standing of top Chinese universities, it has since 2009 been maintained by the ShanghaiRanking Consultancy.

The ARWU ranks more than 1,800 universities every year, and the best 1,000 are published. It uses a combination of six objective indicators that are weighted as follows:

  1. number of alumni who win Nobel Prizes and Fields Medals (10%)
  2. number of staff who win Nobel Prizes and Fields Medals (20%)
  3. number of highly cited researchers in 21 broad subject categories (20%)
  4. number of papers published in Nature and Science (20%)
  5. number of papers indexed in Science Citation Index-expanded and Social Sciences Citation Index (20%)
  6. per capita academic performance of an institution (10%)

While the ARWU is noted for its methodology and influence, its heavy weighting towards more traditional measures of research excellence makes it difficult for high-performing yet younger, smaller or less well-known institutes to get a look-in.

For 2019, its top 10 rankings are unchanged from 2018, with Harvard University scoring a perfect 100 out of 100, followed by Stanford University, at 75.1.

Of the three ranking systems described here, the ARWU shows by far the greatest spread in total scores across the top 10 institutions, with Harvard at first place separated by the University of Chicago in tenth place by 44.9 points.


Times Higher Education (THE) World University Rankings

Originally partnered with Quacquarelli Symonds (QS) to publish the joint THE-QS World University Rankings from 2004 to 2009, Times Higher Education (at the time known as the Times Higher Education Supplement) sought out Thomson Reuters to devise and publish a new ranking methodology in 2010.

Since then, it has become one of the most widely considered global ranking systems for higher education institutions.

It considers 13 separate performance indicators to judge universities against their key missions, including teaching, research, knowledge transfer and international outlook.

These performance indicators are grouped into five areas:

1. Teaching (the learning environment) – 30%

  • Reputation survey: 15%
  • Staff-to-student ratio: 4.5%
  • Doctorate-to-bachelor’s ratio: 2.25%
  • Doctorates-awarded-to-academic-staff ratio: 6%
  • Institutional income: 2.25%

2. Research (volume, income and reputation) – 30%

  • Reputation survey: 18%
  • Research income: 6%
  • Research productivity: 6%

3. Citations (research influence) – 30%

4. International outlook (staff, students, research) – 7.5%

  • Proportion of international students: 2.5%
  • Proportion of international staff: 2.5%
  • International collaboration: 2.5%

5. Industry income (knowledge transfer) – 2.5%

If an institution does not teach undergraduates, only teaches a narrow subject area, or does not produce a large number of research articles, it will not be considered in these rankings. This means that certain smaller or highly specialist institutions might not be included.

In compiling its World University Rankings 2019 top 1,000 table, THE analyzed data on more than 1,250 universities worldwide, and conducted a global Academic Reputation Survey of more than 20,000 leading scholars.

It also analyzed 67.9 million citations to more than 14.1 million academic journal articles (from Elsevier’s Scopus database) published between 2013 and 2017.

In its top 10, the number one seed, the University of Oxford, is separated from the number 10 seed, the University of Chicago, by just 5.8 points – a much tighter spread than ARWU’s top 10.


QS World University Rankings

The QS World University Rankings places a strong emphasis on reputation.

The rankings compare universities in four major areas: research, teaching, employability, and international outlook, and each of these areas are measured against six performance indicators:

1. Academic reputation – 40%

Based on an academic survey, it collates the expert opinions of more than 94,000 experts regarding teaching and research quality.

2. Faculty/Student Ratio – 20%

The number of academic staff employed relative to the number of students enrolled.

3. Citations per faculty – 20%

The total number of citations received by all papers produced by an institution across a five-year period by the number of faculty members at that institution. To account for the fact that different fields have very different publishing cultures – papers concerning the life sciences are responsible nearly half of all research citations as of 2015 – citations are normalized.

4. Employer reputation – 10%

Based on an employer survey, which collates 45,000 responses from employers about which institutions they source the most competent, innovative, effective graduates from.

5 and 6. International faculty/student ratio – 5% each

A measure of an institution’s success in attracting faculty and students from overseas.

Like THE’s rankings, to be eligible for inclusion, institutions must teach at both undergraduate and postgraduate levels and conduct work in at least two of five broad faculty areas (arts and humanities; engineering and technology; social sciences and management; natural sciences; life sciences and medicine).

The QS rankings have been criticized for the heavy weighting they put on opinion surveys, which are, by design, not objective measures, though they are the largest surveys of their kind in the world.

Highly prestigious institutions, which are well known and highly regarded, are at the biggest advantage when being measured by opinion-based metrics.

Like THE’s World University Rankings for 2019, the QS rankings for 2019 reveal a mere 7.1-point separation between the Massachusetts Institute of Technology (MIT) in the number one slot and University College London (UCL) in tenth place.

MIT has scored 100 out of 100 consistently since 2012.


Nature Index

Each year, the Nature Index publishes tables based on counts of high-quality research outputs in the natural sciences.

In 2018, it increased the number of journals it tracked from 68 to 82, to account for newly established high-quality publications, and to increase the coverage of articles in the Earth and environmental sciences and the life sciences.

The 82 journals were selected by a panel of active scientists, independent of Nature Research, based on their perceptions of journal quality, rather than using quantitative measures such as the Journal Impact Factor. These journals account for close to 30% of total citations to natural science journals.

The Nature Index tracks more than 58,000 institutions worldwide (which includes approximately 9,000 root institutions and their ‘children’), and research output is measured by:

  1. Article count (AC): a count of one is assigned to an institution/country if one or more authors of the article are from that institution/country, regardless of how many co-authors there are from outside that institution/country.

  2. Fractional count (FC): takes into account the percentage of authors from a particular institution (or country) and the number of affiliated institutions per article. For calculation of the FC, all authors are considered.

Research outputs tracked by the Nature Index are non-normalized, which means they don’t take into account the size of the country or institution, or its overall research output.

In 2019, the Nature Index also published a normalized annual table, revealing the smaller institutions that punched above their weight in 2018.



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