IR

Welcome to SIGIR 2019, the 42nd Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, the premier scienti c conference in the broad area of information retrieval. We are delighted to welcome you to the Museum of Science and Industry located in the north-east of Paris. The conference is supported by the French Association for Information Retrieval and Applications, which organizes the yearly French IR conference. Its members actively participated in the organization of this conference.

We received good quality submissions in all tracks and events: full papers, short papers, demos, industry papers, tutorials, workshops, and the doctoral consortium. We would like to thank everyone who contributed to the paper selection process, including 100 Senior Program Committee (SPC) members, 317 Program Committee (PC) members, and 80 additional reviewers for their contributions to paper selection.

For the full paper track, we had 426 valid submissions, out of which 84 papers were accepted. We were happy to observe the highest number of submissions since 2013, again passing the 400 submission bar (as started last year with 409 valid submissions). This trend suggests a renewed interest in our eld, and we hope that we will soon again exceed 500 submissions as in 2010 (Geneva) and 2011 (Beijing). In terms of acceptance rate, we reached 19.7%, which is in the range [15.5% - 21.5%] of past acceptance rates.

The submissions were made by 1480 authors from 38 countries: 141 papers were contributed by 557 authors from China (taking all author affiliations of each paper equally into account), 99 papers by 323 authors from the United States, and 186 papers by 600 authors from the rest of the world. The top ve countries in terms of accepted papers are: China (36), the United States (22), Australia (4.7), Singapore (3.8) and Netherlands (3.2). In terms of acceptance rate, Chile (83%), Denmark (44%), Finland (44%), the Netherlands (44%), and Australia (30%) were the top ve countries. Among the topic areas, Content Analysis, Recommenda-tion and Classi cation is the most popular area (with 197 submissions and 34 accepted papers), followed by Search and Ranking (127 submissions and 26 accepted), Arti cial Intelligence, Semantics, and Dialog (94 submissions and 18 accepted), Domain-Speci c Applications (82 submissions and 10 accepted), Human Factors and Interfaces (45 submissions and 11 accepted), Future Directions (41 submissions and 4 accepted) and Evaluation (31 submissions and 7 accepted).

SIGIR 2019 used a two-tier double-blind review process. For all papers, 3 PC members and 1 SPC member were assigned to provide rst-round reviews. Subsequently, if the SPC member believed that the review process would bene t from additional expert opinion, a further SPC member was assigned to provide a second-round review. The rst SPC would then make a preliminary recommendation. The recommenda-tions, reviews and discussions held on EasyChair between all assigned SPC and PC members were carefully examined and nal acceptance decisions made at the in-person PC meeting held in Koln, Germany, on April 11-12, 2019. Video conferencing was provided at the PC meeting to allow remote participation of additional SPC members. The program committee carefully reviewed all 426 valid submissions, and each received three or more reviews and a metareview. 32 additional reviews were then conducted by the SPC members, which provided further feedback to the authors of the discussed papers.