According to Janez Potocnik, former European Commissioner for science and research, world university rankings are now used by politicians "as a measurement of their nation's economic strength and aspirations".

They are also employed by universities to define performance targets, while academics use them to support their own research, the commissioner says in the final report from the European Commission's Expert Group of Assessment of University-Based Research.

So, as a publication that seeks to rank universities, Times ÖйúAƬ is aware of its responsibility to do a rigorous job. We are also aware of the limitations of the rankings we ran from 2004 to 2009.

A key concern, the report says, is that "ranking universities as entire institutions may not be the most appropriate way to identify where the best research is done".

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It is with this in mind that THE can confirm a fresh approach. We will continue to rank the top 200 universities as a whole, but from 2010, the tables will be built from the subject level upwards.

Our previous rankings included subject tables in five areas, but these were based on a single criterion of the six used to compile the overall rankings - the reputational survey, with all the limitations that entailed.

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From 2010, with our new data partner Thomson Reuters, we will examine institutions' strengths in six broad subject areas: arts and humanities; social sciences; life sciences; physical sciences; engineering and technology; and clinical, pre-clinical and health.

We will also judge subject strength on the full range of measures used in the overall table. We believe this will represent another great improvement.