Exploring Project Connections Across the Citizen Science Landscape: A Social Network Analysis of Shared Volunteers

Research on citizen science volunteers has historically focused on single projects, but emerging research suggests many volunteers engage in multiple projects. Platforms that host thousands of projects, like SciStarter.org, enable exploration of volunteer activity across multiple projects. To learn more about the phenomenon of multi-project engagement, we carried out a descriptive social network analysis using digital trace data depicting volunteer activity on SciStarter.org from 2017 to 2018. During this time period, our sample included 624 citizen science projects and 3,650 unique volunteers that engaged in these projects. We used these data to visualize and analyze project connection networks formed when volunteers join multiple projects. Volunteers joined an average of 2.93 projects spanning many different scientific disciplines (e.g., topics such as Health & Medicine, Ecology & Environment) and modes of participation (e.g., online, offline); 73% of volunteers joined 2 or more projects. Volunteer engagement in citizen science produced a complex network of project connections with low network centrality, low levels of homophily and clustering, and ample evidence of boundary spanning (e.g., based on topic or mode). The projects most central in the network, which were also the most popular, were those featured as affiliates on the website or in promotional email campaigns. By using a network approach to analyze digital trace data, our research illustrates the extent of multi-project, multi-disciplinary engagement on a third-party platform, laying the groundwork for researchers and platform managers to explore and facilitate multi-project engagement and its implications for the larger field of citizen science.