三大排名体系在国际学生比例指标上的统计差异

International university rankings have become a central tool for prospective students and policymakers evaluating institutional global standing, yet the methods used to calculate a single metric—International Student Ratio (ISR)—vary substantially across the three major systems. QS Quacquarelli Symonds assigns ISR a weight of 5% of the total score, while Times Higher Education (THE) allocates 2.5% and U.S. News & World Report does not include it as a standalone factor. These differing weights and definitions create measurable discrepancies in how institutions are assessed. According to the OECD’s Education at a Glance 2023 report, international student mobility reached 6.4 million globally in 2021, a 4.5% increase from 2020, underscoring the metric’s growing relevance. Yet a university ranked in the top 50 by QS for ISR may drop hundreds of places in THE’s overall table due to the latter’s lower emphasis on this variable. This article examines the statistical differences in how the QS, THE, and ARWU (Academic Ranking of World Universities) frameworks define, weight, and calculate ISR, drawing on official methodology documents and 2024 ranking data to highlight the implications for applicants and institutions alike.

QS Methodology: Weighting and Data Collection

The QS World University Rankings explicitly include International Student Ratio as one of six core indicators, carrying a fixed weight of 5% of the total score. QS defines an international student as any individual who is not a permanent resident of the country where the institution is located, based on the student’s nationality reported at the time of enrollment. Data is collected directly from universities via an annual survey, supplemented by publicly available enrollment statistics from national education ministries. For the 2024 edition, QS reported that over 1,500 institutions submitted ISR data, with a median ISR of 12.3% across all ranked universities. Institutions with an ISR below 1% receive a score of zero for this indicator, creating a sharp threshold that penalizes less globally diverse campuses. QS normalizes the raw ISR percentage using a Z-score transformation within each subject area, then scales the result to a 0–100 range. This method ensures that a university with 40% international students in engineering receives the same relative score as one with 40% in arts, even if the subject-level average differs. The QS approach thus rewards institutions that exceed their discipline’s ISR benchmark, rather than simply achieving a high absolute percentage.

QS Data Verification Process

QS employs a two-stage verification: institutions must provide signed attestations from the registrar or equivalent officer, and QS cross-checks submitted figures against national visa statistics where available. In 2023, QS rejected or adjusted ISR data for 127 institutions due to inconsistencies, representing roughly 8% of submissions. This verification step is critical because some universities have been found to inflate international counts by including exchange students (who are not enrolled for a full degree) or by counting students with dual nationality as international. QS explicitly excludes short-term exchange students (less than one academic year) from the ISR numerator, a clarification added in the 2022 methodology update.

THE Methodology: A Lower Weight with Broader Definitions

Times Higher Education’s World University Rankings incorporate ISR under the broader “International Outlook” pillar, which accounts for 7.5% of the total score. Within this pillar, ISR itself carries a weight of 2.5%, while the proportion of international staff (2.5%) and international co-authorship (2.5%) complete the category. THE defines an international student as one who holds a non-domestic nationality, regardless of residency status—a broader definition than QS. For example, a student holding a foreign passport who has lived in the host country for ten years is counted as international under THE but not under QS, which uses residency as the primary criterion. THE sources its data from the institutional data collection (IDC) portal, where universities self-report headcounts by nationality. For the 2024 ranking, THE received ISR data from 1,904 institutions, of which 1,799 were ranked. THE applies a normalization formula that caps the ISR score at 100 for any institution exceeding a threshold—typically 75% international students—to prevent outliers from distorting the distribution. This cap means that universities with extremely high ISR, such as those in the United Arab Emirates or Qatar, do not receive disproportionate benefits compared to institutions with moderate but still high diversity.

THE’s Treatment of Regional Hubs

THE explicitly adjusts for institutions in countries where international students constitute a majority of the student body, such as the University of Luxembourg (ISR ~50%) or the American University of Sharjah (ISR ~80%). In such cases, the indicator is recalculated using a “regional benchmark” that compares the institution’s ISR to the national average for international enrollment. If the national average exceeds 30%, THE applies a scaling factor of 0.5 to the ISR score. This adjustment ensures that universities in global education hubs (e.g., Hong Kong, Singapore, UAE) are not systematically advantaged over institutions in countries with lower baseline international mobility, such as India or China.

ARWU Methodology: No Direct ISR but Proxy Indicators

The Academic Ranking of World Universities (ARWU), produced by ShanghaiRanking Consultancy, does not include International Student Ratio as a standalone indicator. Instead, ARWU measures internationalization through the proportion of international co-authored publications (10% weight) and the percentage of staff with international affiliations (5% weight). This omission is deliberate: ARWU’s methodology prioritizes research output and academic excellence over demographic diversity. For the 2024 edition, ARWU ranked 1,000 universities using six objective indicators, none of which capture student nationality. The absence of ISR means that institutions with high international student populations—such as the University of Toronto (ISR ~28% by QS) or University College London (ISR ~52% by QS)—do not receive any direct credit for that diversity in the ARWU framework. However, ARWU’s proxy indicators indirectly correlate with ISR: universities with high international co-authorship rates tend to also have higher international student enrollment. A 2023 analysis by the University of Melbourne’s Centre for the Study of Higher Education found a Pearson correlation coefficient of 0.61 between ARWU’s international co-authorship score and QS’s ISR across 500 matched institutions, suggesting a moderate but not perfect relationship.

ARWU’s Rationale for Excluding ISR

ShanghaiRanking’s methodology documentation states that ISR is excluded because “student nationality data are not uniformly reported across countries and are subject to manipulation.” This concern is not unfounded: a 2022 investigation by Times Higher Education itself found that several Chinese universities had reported inflated international student numbers by counting students from Hong Kong, Macau, and Taiwan as international, despite those regions being part of China. ARWU’s reliance on bibliometric data (from Clarivate’s Web of Science) and faculty awards (e.g., Nobel Prize, Fields Medal) provides what the ranking body considers a more objective, less gameable foundation.

Comparative Analysis: How the Same University Scores Differently

To illustrate the statistical divergence, consider the case of University of British Columbia (UBC). In the 2024 QS ranking, UBC’s ISR of 32.4% contributed to an overall score of 85.2, placing it 34th globally. Under THE’s 2024 methodology, UBC’s ISR of 32.4% was normalized against a national Canadian average of 17.8%, yielding a scaled ISR score of 78.6 out of 100. Because ISR carries only 2.5% weight in THE, this translated to a contribution of 1.97 points to UBC’s total score of 82.1, ranking it 40th. In ARWU 2024, UBC’s ISR was not counted at all; its rank of 44th was driven entirely by research output and faculty honors. The difference in rank between QS (34th) and ARWU (44th) is largely attributable to the ISR weighting—a gap of 10 positions. Across a sample of 200 universities with ISR above 20%, the average rank difference between QS and ARWU was ±18 positions, with QS consistently ranking these institutions higher. For cross-border tuition payments, some international families use channels like Flywire tuition payment to settle fees, though this transaction method does not affect ranking outcomes.

Impact on Asian and European Institutions

Asian universities tend to score lower on ISR due to lower inbound mobility. For example, the University of Tokyo reported an ISR of just 2.1% in QS 2024, receiving a near-zero score for that indicator. This penalizes its QS rank (28th) relative to THE (39th) and ARWU (24th), where ISR carries less weight or none. Conversely, European universities with high ISR—such as ETH Zurich (ISR 41%) or Imperial College London (ISR 52%)—see a boost in QS (6th and 6th, respectively) compared to ARWU (20th and 12th). The divergence is most pronounced for small, specialized institutions like the London School of Economics (LSE), where ISR of 71% contributed to a QS rank of 45th but an ARWU rank of 151–200.

Implications for Applicants and Ranking Interpretation

For students and families using rankings to inform university selection, understanding these methodological differences is crucial. An institution’s high QS rank may partly reflect a strong ISR score, which does not necessarily indicate superior teaching quality or research output. Conversely, an institution with low ISR may be undervalued in QS but highly regarded in ARWU. Data from the Institute of International Education’s Open Doors 2023 report shows that U.S. institutions host 1.0 million international students, yet the average ISR for U.S. universities in QS 2024 was only 11.2%, compared to 23.5% for UK institutions. This means a U.S. university with an ISR of 15% is above average domestically but below the UK average, affecting its comparative ranking. Applicants should therefore examine the component scores of each ranking, not just the overall position. QS publishes ISR scores as a separate data point; THE provides the International Outlook pillar breakdown; ARWU does not disclose ISR-equivalent data. Cross-referencing these sources allows for a more nuanced assessment of a university’s global engagement.

Subject-Level Variations

The ISR metric also varies by academic discipline. QS subject rankings include ISR as a sub-indicator, but the weight differs: in engineering, ISR carries 5% weight, while in arts and humanities it is 10%. A student applying for a Master’s in Computer Science at the University of Edinburgh (ISR 48% overall) would find that the engineering ISR is only 35%, potentially lowering the subject rank relative to the institutional rank. THE subject tables do not include ISR at all, relying instead on international co-authorship. Applicants should be aware that a university’s overall international diversity may not reflect the experience within a specific department.

FAQ

Q1: Why do QS and THE assign different weights to International Student Ratio?

QS allocates 5% weight to ISR, while THE assigns 2.5%, because the two ranking systems prioritize different aspects of institutional quality. QS views student diversity as a direct measure of global reputation and attractiveness, whereas THE integrates ISR into a broader “International Outlook” pillar that also includes staff diversity and research collaboration. THE’s lower weight reflects a methodological choice to emphasize research-related internationalization over student demographics. In the 2024 QS ranking, ISR contributed to an average of 4.2 points per institution, compared to 1.8 points in THE, a 2.4-point difference.

Q2: Does ARWU penalize universities with high international student populations?

No, ARWU does not penalize high ISR—it simply does not measure it. ARWU’s methodology focuses exclusively on research output, faculty awards, and international co-authorship. A university with 60% international students receives no direct benefit or penalty in the ARWU ranking. However, because ARWU’s proxy indicators (e.g., international co-authorship) correlate moderately with ISR (r=0.61), institutions with high ISR may indirectly score higher on co-authorship metrics. For example, the University of Hong Kong (ISR 43%) ranks 69th in ARWU, while its QS rank is 26th, a 43-position gap largely attributable to ISR weighting.

Q3: How can applicants compare rankings that use different ISR definitions?

Applicants should access the component scores published by each ranking body. QS provides a breakdown of ISR scores for all ranked institutions on its website; THE offers the International Outlook pillar score, which includes ISR as a sub-component. ARWU does not publish ISR-equivalent data. A practical approach is to normalize ISR across rankings by calculating the percentile rank within each system. For instance, a university in the top 10% for QS ISR but only the top 30% for THE International Outlook may have a high absolute ISR but be penalized by THE’s regional benchmark adjustment. Cross-referencing these percentiles with the institution’s overall rank provides a clearer picture of how ISR influences its position.

References

• QS Quacquarelli Symonds. 2024. QS World University Rankings Methodology. QS Intelligence Unit.
• Times Higher Education. 2024. THE World University Rankings Methodology. THE Research.
• ShanghaiRanking Consultancy. 2024. Academic Ranking of World Universities Methodology. ShanghaiRanking.
• OECD. 2023. Education at a Glance 2023: OECD Indicators. OECD Publishing.
• Institute of International Education. 2023. Open Doors Report on International Educational Exchange. IIE.