Ranking lists originally began at the national level, comparing universities or specific university activities within a clearly defined political and cultural region. Recently, rankings have been placed on an international level (e.g. the entire German speaking region, Europe) or on a global level as in the case of the Shanghai and THES rankings. This has resulted in universities being compared internationally and across very different settings.
Moving up to international and global levels reflects the progressive internationalization of educational activities. While research has always had an international dimension, internationalization of teaching as well as continuous and executive education is a more recent phenomenon. International activities, programmes and markets, however, need comparative information on an international scale in order to function properly. International ranking lists - like international accreditations - are offering highly condensed comparative information. But how useful is this information? And how reliable is it? How reliable can it be, if very differently structured universities are compared across very different settings on an international scale?
One thing is certain: the wider the boundaries and the more diverse the settings, the less valid the ranking results will be. Beyond differences that lie in the structures and strategies of the universities themselves, there is a serious problem of available statistical information at an international level. This relates to student and faculty data, to data concerning the teaching and learning processes as well as the learning outcomes. But this also relates to the promotion of young researchers and research outcomes if we move beyond available bibliographic data. This applies to some areas (mainly in the natural and life sciences) and entails communication through international scientific journals, usually in English.
In addition, there is a major problem of interpreting statistical and other information across very different institutional, political and cultural settings. The degree of independence in running a university, in employing, promoting and laying-off faculty may differ widely between different systems. There may also be differing degrees of freedom in selecting students, from inside or from outside one’s own country. The financial means available to universities and their ability to acquire new funds may be very different, depending on their legal status and mission, and reliant on public budgets. It is important to know whether there are 3500 (USA), 540 (France), 300 (Germany) or 39 higher education institutions as in the case of Switzerland. We should also know whether these universities are intended to serve their country's needs and whether universities are expected to compete with each other or not. And it is also important to know whether they are located in culturally specific environments, having to serve the particular needs of these environments. Also, the international language of science is English.