Stephen Robertson joined Microsoft Research Cambridge in April 1998.
At Microsoft, he started an informal group called Information Retrieval and Analysis, which is concerned with core search processes such as term weighting, document scoring and ranking algorithms, combination of evidence from different sources, and with metrics and methods for evaluation and for optimisation. These are studied theoretically through the use of formal models, mainly statistical, and statistical methods including machine learning methods, and experimentally, through activities such as the Text Retrieval Conference (TREC) and with internally generated evaluation sets. The group (with its Keenbow evaluation environment) has had some excellent results at TREC. The group works closely with product groups to transfer ideas and techniques.
His main research interests are in the design and evaluation of retrieval systems. He is the author, jointly with Karen Sparck Jones, of a probabilistic theory of information retrieval, which has been moderately influential. A further development of that model, with Stephen Walker, led to the term weighting and document ranking function known as Okapi BM25, which is used in many experimental text retrieval systems. At Microsoft, he developed a field-aware version called BM25F.
Prior to joining Microsoft, he was at City University London, in the Department of Information Science. He was Head of Department for eight years, during which time it achieved the highest possible rating in two successive research assessment exercises. He also started the Centre for Interactive Systems Research, the main research vehicle of which is the Okapi text retrieval system, which has also done well at TREC.
Before joining City, he was a research fellow at University College London, where he took his PhD in the School of Library Archive and Information Studies under B.C. Brookes. Before that he was in the research department at Aslib. He has an MSc in Information Science from City and a first degree in mathematics from Cambridge.
He is currently Professor Emeritus at City University (homepage), Visiting Professor at University College London, and Fellow of Girton College Cambridge.
A selected list of publications is here; slides of a talk given in November 1999 at Carnegie-Mellon University and the University of Pittsburgh, and some more from the ESSIR summer school in Varenna in September 2000. Papers on the Okapi and Keenbow systems at TREC are available here. The text of the Salton Award lecture is here. The Sparck Jones / Robertson IDF page is here. A large paper reviewing developments of the probabilistic models is here, and there is a tutorial paper here.
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Last updated October 2012