The World University Rankings are compiled using a mixture of quantitative indicators and informed opinion

What makes a world-class university? When Times Higher Education asked the leaders of top-ranked institutions this question last year, one response stood out for its inspirational qualities.

Robert Zimmer, president of the University of Chicago, said that his institution was "driven by a singular focus on the value of open, rigorous and intense inquiry. Everything about the university that we recognise as distinctive flows from this."

He said that Chicago believed that "argumentation rather than deference is the route to clarity", that "arguments stand or fall on their merits" and that the university recognised that "our contributions to society rest on the power of our ideas and the openness of our environment to developing and testing ideas".

His answer prompted much praise. One Times Higher Education reader said that Zimmer's "glorious affirmation" was "marvellously refreshing" and had "brought joy to my heart, tears to my eyes and a renewed sense of commitment to the life of the mind".

But glorious as Zimmer's statement was, it also served to highlight the problem faced by the increasing number of people and organisations now in the business of ranking higher education institutions: how on earth do you measure such intangible things?

The short answer, of course, is that you cannot. What you can do, however, and what we have sought to do with these rankings, is to try to capture the more tangible and measurable elements that make a modern, world-class university.

When Times Higher Education first conceived its annual World University Rankings with QS in 2004, we identified "four pillars" that supported the foundations of a leading international institution. They are hardly controversial: high-quality research; high-quality teaching; high graduate employability; and an "international outlook".

Much more controversial are the measurements we chose for our rankings, and the balance between quantitative and qualitative measures.

To judge research excellence, we examine citations - how many times an academic's published work is cited.

We calculate this element - worth 20 per cent of the overall score - by taking the total number of citations for all papers published from the institution, and then dividing the figure by the number of full-time equivalent staff at the institution. This gives a sense of the density of research excellence on a campus.

Our proxy for teaching excellence is a simple measure of staff-to-student ratio. It is not perfect, but it is based on data that can be collected for all institutions, often via national bodies, and compared fairly. Our assumption is that it tells us something meaningful about the quality of the student experience. At the most basic level, it at least gives a sense as to whether an institution has enough teaching staff to give students the attention they require. This measure is worth 20 per cent of the overall score.

To get a sense of a university's international outlook, we measure the proportion of overseas staff a university has on its books (making up 5 per cent of the total score) and the proportion of international students it has attracted (making up another 5 per cent). This gives an impression of how attractive an institution is around the world, and suggests how much the institution has embraced the globalisation agenda.

But 50 per cent of the final score is made up from qualitative data from surveys of informed people - university academics and graduate employers.

The fundamental tenet of this ranking, as we have said in previous years, is that academics know best when it comes to identifying the best institutions.

So the biggest part of the ranking score - worth 40 per cent - is based on the result of an academic peer review survey. We consult academics around the world, from lecturers to university presidents, and ask them to name up to 30 institutions they regard as being the best in the world in their field.

Responses over the past three years are aggregated, although only the most recent response from anyone who has responded more than once is used. For our 2009 tables, we have drawn on responses from 9,386 people. With each person nominating an average of 13 institutions, this means that we can draw on about 120,000 data points.

The ranking also includes the results of an employer survey of 3,281 major graduate employers, making up 10 per cent of the overall result.

Times Higher Education-QS World University Rankings 2009: full coverage and tables:

2009 rank	2008 rank	INSTITUTION	country	International staff score	International student score	Overall score
1	1	Harvard University	US	85	78	100.0
2	3	University of Cambridge	UK	98	96	99.6
3	2	Yale University	US	85	77	99.1
4	7	University College London	UK	96	99	99.0
5=	6	Imperial College London	UK	98	100	97.8
5=	4	University of Oxford	UK	96	97	97.8
7	8	University of Chicago	US	77	83	96.8
8	12	Princeton University	US	89	81	96.6
9	9	Massachusetts Institute of Technology	US	31	95	96.1
10	5	California Institute of Technology	US	100	89	95.9
11	10	Columbia University	US	28	89	95.6
12	11	University of Pennsylvania	US	82	60	94.2
13	13=	Johns Hopkins University	US	28	71	94.1
14	13=	Duke University	US	29	62	92.9
15	15	Cornell University	US	28	73	92.5
16	17	Stanford University	US	25	96	92.2
17	16	Australian National University	Australia	99	92	90.5
18	20	McGill University	Canada	67	95	90.4
19	18	University of Michigan	US	57	52	89.9
20=	23	University of Edinburgh	UK	93	86	89.3
20=	24	ETH Zurich (Swiss Federal Institute of Technology)	Switzerland	100	94	89.3
22	19	University of Tokyo	Japan	28	42	88.9
23	22	King’s College London	UK	92	88	88.4
24	26	University of Hong Kong	Hong Kong	100	95	87.5
25	25	Kyoto University	Japan	32	26	87.1
26	29	University of Manchester	UK	90	87	85.7
27	21	Carnegie Mellon University	US	62	96	85.6
28	28	Ecole Normale Supérieure, Paris	France	76	61	85.4
29	41	University of Toronto	Canada	82	51	85.3
30	30=	National University of Singapore	Singapore	100	100	84.3
31	27	Brown University	US	53	55	83.9
32=	30=	University of California, Los Angeles	US	21	33	83.5
32=	33	Northwestern University	US	28	100	83.5
34	32	University of Bristol	UK	85	77	83.4
35	39	Hong Kong University of Science and Technology	Hong Kong	100	99	83.3
36=	34=	Ecole Polytechnique	France	63	95	83.1
36=	38	University of Melbourne	Australia	59	97	83.1
36=	37	University of Sydney	Australia	99	95	83.1
39	36	University of California, Berkeley	US	86	34	82.7
40	34=	University of British Columbia	Canada	34	60	81.2
41	43	University of Queensland	Australia	99	82	80.7
42	50=	Ecole Polytechnique Fédérale de Lausanne	Switzerland	100	100	80.6
43=	44	Osaka University	Japan	24	33	80.1
43=	49	Trinity College Dublin	Ireland	98	83	80.1
45	47	Monash University	Australia	95	96	80.0
46	42	Chinese University of Hong Kong	Hong Kong	97	79	79.6
47=	45	University of New South Wales	Australia	82	93	79.0
47=	50=	Seoul National University	South Korea	29	33	79.0
49=	53	University of Amsterdam	Netherlands	71	32	78.9
49=	56	Tsinghua University	China	45	34	78.9
51	48	University of Copenhagen	Denmark	71	73	78.8
52=	40	New York University	US	26	52	78.4
52=	50=	Peking University	China	24	30	78.4
54	46	Boston University	US	25	89	77.8
55=	78=	Technical University of Munich	Germany	56	74	76.3
55=	61	Tokyo Institute of Technology	Japan	31	49	76.3
57	57	Heidelberg University	Germany	58	80	76.2
58	69	University of Warwick	UK	85	97	75.7
59	74	University of Alberta	Canada	91	66	75.4
60	64	Leiden University	Netherlands	74	40	75.3
61=	65	University of Auckland	New Zealand	93	99	74.7
61=	55	University of Wisconsin-Madison	US	29	36	74.7
63=	81=	Aarhus University	Denmark	69	66	74.5
63=	71	University of Illinois at Urbana-Champaign	US	72	49	74.5
65	72	Katholieke Universiteit Leuven	Belgium	55	55	74.2
66	75	University of Birmingham	UK	83	76	73.9
67=	66	London School of Economics	UK	100	100	73.7
67=	88	Lund University	Sweden	57	62	73.7
69	95	Korea Advanced Institute of Science and Technology	South Korea	47	31	72.6
70=	67	Utrecht University	Netherlands	43	24	72.4
70=	81=	University of York	UK	95	83	72.4
72	68	University of Geneva	Switzerland	97	100	72.3
73=	77	Nanyang Technological University	Singapore	100	100	72.0
73=	60	Washington University in St Louis	US	30	53	72.0
75	63	Uppsala University	Sweden	68	40	71.9
76=	58	University of California, San Diego	US	22	27	71.5
76=	70	University of Texas at Austin	US	55	41	71.5
78	102=	University of North Carolina, Chapel Hill	US	23	26	71.3
79	73	University of Glasgow	UK	58	60	71.2
80	59	University of Washington	US	25	36	71.1
81	106=	University of Adelaide	Australia	87	96	70.8
82	76	University of Sheffield	UK	81	76	70.6
83	78=	Delft University of Technology	Netherlands	84	73	70.4
84	83=	University of Western Australia	Australia	99	87	70.2
85	54	Dartmouth College	US	34	52	70.1
86	83=	Georgia Institute of Technology	US	36	77	70.0
87=	99=	Purdue University	US	94	60	69.8
87=	83=	University of St Andrews	UK	91	99	69.8
89	108	University College Dublin	Ireland	95	90	69.7
90	62	Emory University	US	41	45	69.6
91	86	University of Nottingham	UK	84	86	69.4
92=	120	Nagoya University	Japan	28	34	69.2
92=	106=	University of Zurich	Switzerland	99	71	69.2
94	137=	Free University of Berlin	Germany	49	63	69.0
95=	99=	University of Southampton	UK	86	76	68.9
95=	124=	National Taiwan University	Taiwan	29	25	68.9
97	112	Tohoku University	Japan	36	32	68.6
98	93=	Ludwig-Maximilians University, Munich	Germany	53	66	68.4
99	104	University of Leeds	UK	75	62	68.3
100	78=	Rice University	US	38	67	68.1
101	177=	University of Oslo	Norway	32	58	67.7
102	93=	Hebrew University of Jerusalem	Israel	61	32	67.3
103=	122=	Durham University	UK	91	69	67.2
103=	113	Fudan University	China	29	47	67.2
105	87	University of Minnesota	US	84	38	67.1
106	98	University of California, Santa Barbara	US	37	21	66.6
107	91=	Université de Montréal	Canada	82	74	66.2
108=	131	University of Basel	Switzerland	99	90	66.1
108=	89	University of California, Davis	US	26	25	66.1
108=	126	Erasmus University Rotterdam	Netherlands	57	65	66.1
108=	91=	University of Helsinki	Finland	29	21	66.1
112	102=	University of Southern California	US	66	88	66.0
113	129	University of Waterloo	Canada	71	41	65.8
114=	97	University of Pittsburgh	US	73	35	65.6
114=	114	Tel Aviv University	Israel	35	20	65.6
116	111	Maastricht University	Netherlands	66	100	65.3
117	149	Université Pierre-et-Marie-Curie Paris VI	France	27	88	65.0
118	117=	Queen’s University	Canada	68	34	64.7
119	90	Case Western Reserve University	US	20	52	64.6
120=	128	Eindhoven University of Technology	Netherlands	99	39	64.4
120=	105	Pennsylvania State University	US	38	34	64.4
122=	147=	Freiburg University	Germany	51	76	64.0
122=	122=	University of Maryland, College Park	US	55	38	64.0
124	147=	City University of Hong Kong	Hong Kong	100	60	63.9
125	124=	University of Otago	New Zealand	100	83	63.8
126=	116	Université Catholique de Louvain	Belgium	47	72	63.7
126=	140	Ecole Normale Supérieure de Lyon	France	55	60	63.7
128	96	University of Virginia	US	22	36	63.5
129=	153	University of Aberdeen	UK	90	87	63.4
129=	110	Georgetown University	US	24	51	63.4
129=	121	Ohio State University	US	69	46	63.4
132=	109	Technion – Israel Institute of Technology	Israel	18	17	63.0
132=	115	University of Vienna	Austria	65	77	63.0
134	188=	Pohang University of Science and Technology	South Korea	50	19	62.9
135	133=	Cardiff University	UK	70	72	62.8
136	136	University of Ghent	Belgium	49	34	62.6
137	133=	University of Liverpool	UK	78	64	62.4
138=	166=	Chulalongkorn University	Thailand	28	14	62.3
138=	144=	University of Groningen	Netherlands	62	49	62.3
140	101	Vanderbilt University	US	54	36	62.2
141	119	University of Rochester	US	61	63	61.8
142	214	Keio University	Japan	24	18	61.6
143	117=	McMaster University	Canada	27	31	60.9
144=	152	University of Bath	UK	89	94	60.7
144=	227	University of Bergen	Norway	60	64	60.7
146=	179	University of Cape Town	South Africa	77	86	60.6
146=	139	Humboldt University of Berlin	Germany	45	59	60.6
148	180=	Waseda University	Japan	41	30	60.5
149=	170=	University of Calgary	Canada	47	31	60.4
149=	155=	Eberhard Karls University of Tübingen	Germany	53	50	60.4
151=	159	University of Western Ontario	Canada	70	27	60.3
151=	203	Yonsei University	South Korea	22	31	60.3
153	144=	Shanghai Jiao Tong University	China	32	16	60.2
154	141	University of Science and Technology of China	China	17	13	60.1
155=	158	Kyushu University	Japan	19	34	60.0
155=	183=	Lomonosov Moscow State University	Russia	76	44	60.0
155=	142	Wageningen University	Netherlands	39	97	60.0
158	162=	Newcastle University	UK	81	86	59.6
159	133=	Technical University of Denmark	Denmark	93	47	59.5
160	157	Tufts University	US	100	43	59.4
161	132	University of California, Irvine	US	26	35	59.0
162	170=	Lancaster University	UK	85	81	58.9
163	174=	Indian Institute of Technology Bombay	India	16	13	58.6
164	160	Queen Mary, University of London	UK	92	90	58.5
165	155=	VU University Amsterdam	Netherlands	39	28	58.3
166=	146	University of Arizona	US	27	32	58.0
166=	130	University of Sussex	UK	87	80	58.0
168=	161	University of Lausanne	Switzerland	88	80	57.4
168=	143	Nanjing University	China	50	17	57.4
168=	224	Saint-Petersburg State University	Russia	16	20	57.4
171=	186=	University of Barcelona	Spain	24	37	57.2
171=	174=	Hokkaido University	Japan	19	25	57.2
173	127	Stony Brook University	US	61	87	57.1
174=	192=	University of Bologna	Italy	27	29	56.9
174=	173	KTH, Royal Institute of Technology	Sweden	83	98	56.9
174=	216	University of Tsukuba	Japan	23	36	56.9
177=	195	University of Antwerp	Belgium	59	56	56.7
177=	200=	University of Athens	Greece	0	91	56.7
179	137=	Texas A&M University	US	32	35	56.6
180	230	Universiti Malaya	Malaysia	72	65	56.5
181	154	Indian Institute of Technology Delhi	India	15	13	56.4
182	216	Rheinisch-Westfälische Technische Hochschule Aachen	Germany	50	66	56.3
183	151	Rutgers, The State University of New Jersey	US	61	28	56.2
184	207	University of Karlsruhe	Germany	49	81	56.1
185	258	University of Gothenburg	Sweden	65	86	55.8
186=	180=	University of Colorado at Boulder	US	36	20	55.6
186=	166=	University of Göttingen	Germany	40	49	55.6
188	186=	University of Canterbury	New Zealand	99	82	55.2
189	182	Macquarie University	Australia	86	100	54.9
190	150	National Autonomous University of Mexico	Mexico	35	15	54.8
191=	183=	Université Libre de Bruxelles	Belgium	57	96	54.7
191=	194	University of Reading	UK	80	81	54.7
193=	192=	University of Bern	Switzerland	92	44	54.5
193=	170=	Indiana University Bloomington	US	46	48	54.5
195	224	Hong Kong Polytechnic University	Hong Kong	100	75	54.4
196=	177=	University of Leicester	UK	72	94	53.9
196=	164	Simon Fraser University	Canada	88	49	53.9
198	162=	Chalmers University of Technology	Sweden	44	57	53.8
199	168	University of Notre Dame	US	25	31	53.6
200	200=	University of Twente	Netherlands	83	66	53.5