IR

Welcome to SIGIR 2016, the 39th Annual International ACM-SIGIR Conference on Research and Development in Information Retrieval, the premier conference in the area. We are grateful to all those who chose to submit their research papers to SIGIR 2016 and gave the Program Committee an opportunity to evaluate their work for potential inclusion in the program. We are also grateful to the 61 Senior Program Committee Members, 244 Program Committee Members, and many additional reviewers for providing significant time and effort to selecting this year's conference program. This pool of committed SIGIR volunteers comes from 24 countries and over 180 institutions.

The PC reviewed 341 papers for the full paper track, and accepted 62 with an acceptance rate of 18%. The top countries in terms of accepted papers (taking all author affiliations of each paper equally into account) were the U.S.A. (34%), and China (23%) with the most successful countries (as measured by how likely authors from that country were to have their papers accepted) were Russia (55% of authors had their paper accepted), Israel (50%), and Germany (45%). With 1236 authors overall, 313 were from the U.S.A and 283 from China; and 289 from the next six most represented countries combined.

As has been customary for many years, SIGIR 2016 employed a two-tier double-blind review process. At least three reviewers reviewed each paper, and then the Primary Area Chair of the paper led a discussion, which was used as the basis of the meta-review. The Secondary Area Chair assigned to each paper double-checked the reviews and discussion and, in some cases, provided an additional review. The PC chairs carefully examined the reviews and associated discussion, asking for additional reviews where necessary to provide a fuller discussion or additional expert opinion.

The SIGIR 2016 PC meeting operated as a virtual meeting, held over several days, in order tofacilitate the involvement of as many Senior PC members as possible. Prior to the PC meeting the PC chairs proposed a list of "clear accepts" and "clear rejects" where the meta-reviews and reviews clearly indicated a decision. Over the four days of the PC meeting, the chairs indicated which undecided papers were open for discussion, led the discussion on these papers, and made the final decision when discussions moved towards completion; overall nearly half of the submitted papers were reviewed by the chairs or at the meeting. We are grateful for the involvement of the Senior PC members in supporting this PC meeting, especially those very committed members who participated in almost every discussion. The virtual PC meeting was supplemented by a small physical meeting of the Senior PC members who attended the ECIR 2016 conference, which took place during the same week.

The short paper track received 339 submissions and accepted 104 papers for what promises to be a strong short paper track. Thanks are due to Ben Carterette, Carlos Castillo, and Jaana Kekäläinen, the track chairs, for arranging and managing a thorough review process for so many papers -- a huge effort for which we are very grateful.

The tutorial track reviewed 20 submissions and accepted 2 full-day tutorials and 10 half-day tutorials. We are grateful to Evangelos Kanoulas and Tie-Yan Liu for leading the selection of a diverse and high quality tutorial program.

The workshops track received 12 submissions and selected 7 workshop proposals. We thank Aristides Gionis and Edie Rasmussen for their efforts in producing a great set of workshops.

The demos track received 35 submissions of which 21 were accepted. Many thanks are due to Craig Macdonald for chairing this track and providing us with an array of interesting demos.

Brian D. Davison and Kira Radinsky organised the Doctoral Consortium, a vitally important part of the SIGIR program. Thanks to their efforts, the event received 23 submissions from doctoral students and accepted 15 of these for presentation and discussion at the consortium.

This year's industry track is the SIGIR Symposium on IR in Practice (SIRIP 2016) co-chaired by Jussi Karlgren and Gilad Mishne. Their efforts in organizing SIRIP and producing an interesting set of speakers from diverse backgrounds are gratefully acknowledged.