Fecha: Lunes 30 Septiembre a las 11:30

Ponente: Alistair Moffat (University of Melbourne)

Lugar de celebración: Salón de Grados de Industriales, ETSI Industriales, UNED (mapa)


The Information Retrieval community pride themselves on the strength of their evaluation protocols: working with large test collections; executing dozens or hundreds of queries taken to be representative of typical information requirements; and, in many cases, employing expert assessors to form relevance judgments. System scores using these resources are then computed using an effectiveness metric such as precision at depth k, expected reciprocal rank, or average precision; and champion-versus-challenger evaluations are carried out by considering the two system means through the lens of a statistical significance test.

This presentation focuses on the effectiveness metrics that are at the heart of this batch evaluation pipeline. After describing a range of traditional approaches to measuring effectiveness, the "C/W/L" framework is motivated and defined, and a range of implications of this approach to IR evaluation then explored. Notable in the C/W/L structure is the explicit correspondence between metrics and user models. This relationship makes it possible for metrics to be evaluated and compared in terms of their suitability for different types of search task, based on the extent to which the user model associated with each candidate metric correlates with observed user behavior when performing that task. Measurement accuracy is also considered for C/W/L metrics, together with the implications that certain types of user behavior then have on experimental design.


Alistair Moffat has been involved in research in text compression and information retrieval for more than three decades, and has published numerous papers in the areas of index compression, text compression, and dynamic pruning mechanisms, all of which help support efficient ranked querying. Alistair is a co-author of the 1994 (revised 1999) book "Managing Gigabytes", and also co-author of the 2002 book "Compression and Coding Algorithms". Much of Alistair's recent work has examined the issue of IR system evaluation, and, with other co-authors in Australia, he has focused on the relationship between models of user interactions with search results pages, and the effectiveness metrics that those interactions correspond to. Alistair was co-Chair for SIGIR 1998 in Melbourne, and for CIKM 2015, also held in Melbourne; and co-Program Committee Chair for SIGIR 2005 (Salvador, Brazil) and SIGIR 2015 (Santiago, Chile). WSDM, held in Melbourne in February 2019, was Alistair's most recent conference project.

Alistair has been a teaching/research faculty member at the University of Melbourne for thirty years, and was Department Chair from 2007-2011. During his career at Melbourne he has taught programming skills to well in excess of 15,000 undergraduate students, has authored a C programming textbook (Programming, Problem Solving, and Abstraction with C, 2003, revised 2012), and has received awards for his teaching and lecturing skills.

Alistair's PhD was completed in 1985, at the University of Canterbury, in New Zealand, in the area of shortest path algorithms.