UBICOMP

Welcome to the proceedings of the 2013 ACM Joint International Conference on Pervasive and Ubiquitous Computing (UbiComp 2013) -- the first proceedings after the merger of the two most prestigious conferences in the field of Pervasive and Ubiquitous Computing. We were very happy to receive a record number of submissions for this inaugural edition: 305 full papers and 89 notes, for a total of 394 submissions. This is almost exactly the number of submission that the two individual conferences received in 2011 combined! We take this as a sign of strong support from the community, and hope that our efforts of creating an exciting, high quality program this year will ensure that future editions will continue this growth.

We had three aims in this year's edition: to further grow the community with the help of an inclusive program; to maintain the high quality of the constituting conference series Pervasive and UbiComp; and to ensure our review processes could handle the expected growth.

Previously, both Pervasive and UbiComp had average acceptance rates of well below 20% (averaging 17% and 16% in the last 8 years, respectively). We believe that consistently rejecting some 85% of all submitted work does not help with maintaining a healthy and vibrant community. We thus took a cue from the updated submission processes at other premium conference series, such as the ACM Conference on Computer Supported Cooperative Work and Social Computing (CSCW), and introduced a new "revise & resubmit" decision as part of the Program Committee (PC) meeting outcome. "Revise & resubmit" roughly corresponded to the decision "Major Revision Required" in a journal review process: the authors received a detailed set of reviews, along with an editorial "meta review" outlining core issues that needed to be addressed in order to have a chance at being accepted in a second review round. Four weeks later, the original set of PC members who discussed the submission at the PC meeting got together in an online meeting to evaluate the quality of the revised paper. In case all conditions were met, the paper was accepted.

Given the novelty of this process, the Program Committee was relatively cautious with inviting authors for a resubmission. Out of the 394 submission, 71 were accepted or conditionally accepted at the PC meeting, while an additional 34 submissions (8.6% of the total) were invited to revise and resubmit. They were given a concrete list of issues and 4 weeks' time to submit a revision. 29 revisions were received. Out of these, 22 had significantly improved and were ultimately accepted into the program, while for 7 submissions the reviewers found that -- despite the changes -- they were still not ready for publication. We thus have a total of 92 accepted submissions, which not only makes for a healthy 23.4% acceptance rate but also represents the largest program ever in the history of the two conferences -- even when combining all papers presented in a single year at both venues (cf. Figure 2). Overall, we believe that this process helped to grow the breadth and scope of the program while maintaining the high quality expected at a top-tier conference venue like UbiComp.

The above description should also illustrate well the efforts undertaken by this year's Program Committee to gather, select, and improve the work submitted to the conference. This year saw not only the largest number of accepted papers, but also the largest Program Committee ever: 75 PC members, together with over 350 external experts, wrote a total of 1647 reviews in the course of the review process. After further considering each submission via an online discussion forum, 208 submissions (52.7%) were selected for discussion at the two-day face-to-face PC meeting in Paris, France, on May 3-4, 2013. Each of us three PC Chairs moderated a group of roughly 25 PC members, working mostly in parallel but repeatedly synchronizing and calibrating in plenary sessions -- also thanks to the continuing "exchange" of PC members across groups. The parallel sessions saw a frenzy of activity, as additional experts were constantly being drafted from the various meeting rooms by a helpful staff of 6 student volunteers, in order to provide additional input on particular paper discussions elsewhere -- all coordinated by a huge schedule spreadsheet that would consider both conflicts of interests and reviewer availability across all three groups. The amount of expertise and community-history represented by the 70+ PC members present at the meeting was truly invigorating.