Report on the 1st simulation for information retrieval workshop (Sim4IR 2021) at SIGIR 2021.

Simulation is used as a low-cost and repeatable means of experimentation. As Information Retrieval (IR) researchers, we are no strangers to the idea of using simulation within our own field---such as the traditional means of IR system evaluation as manifested through the Cranfield paradigm. While simulation has been used in other areas of IR research (such as the study of user behaviours), we argue that the potential for using simulation has been recognised by relatively few IR researchers so far. To this end, the Sim4IR workshop was held online on July 15^th, 2021 in conjunction with ACM SIGIR 2021. Building on past efforts, the goal of the workshop was to create a forum for researchers and practitioners to promote methodology and development of more widespread use of simulation for IR evaluation. Around 80 participants took part over two sessions. A total of two keynotes, three original paper presentations, and eight 'encore talks' were presented. The main conclusions from the resultant discussion were that simulation has the potential to offer solutions to the limitations of existing evaluation methodologies, but there is more research needed toward developing realistic user simulators; and the development and sharing of simulators, in the form of toolkits and online services, is critical for successful uptake. Date: 15 July, 2021. Website: https://sim4ir.org. [ABSTRACT FROM AUTHOR]