An evaluation of the usability of web-based contiguous cartogram generation tools

Area cartograms are map-based data visualizations in which the area of each map region is proportional to the data value it represents. Long found in print media, area cartograms have also become increasingly popular online, often serving as an accompaniment to news articles and blog posts. Despite their popularity, there is a dearth of cartogram generation tools accessible to non-technical users unfamiliar with Geographic Information Systems software. Few tools support the generation of contiguous cartograms (i.e., area cartograms that faithfully represent the spatial adjacency of neighboring regions). We review existing contiguous cartogram software and compare two web-based cartogram tools: fBlog and go-cart.io. We experimentally evaluated their usability with a user study comprising cartogram generation and analysis tasks. We adopted the System Usability Scale to quantify how participants perceived the usability of both tools. We also collected written feedback from participants to determine the main challenges for users of the software. Participants generally rated go-cart.io as more usable than fBlog. Compared to fBlog, go-cart.io offers a greater variety of built-in maps and allows importing data values by file upload. Still, our results suggest that even go-cart.io suffers from poor usability because the graphical user interface is complex and data can only be imported as a comma-separated-values file. We propose changes to go-cart.io and make general recommendations for web-based cartogram tools to address these concerns.