DOI: 10.14714/CP96.1631 PEER-REVIEWED ARTICLE User-centered Design and Evaluation of a Geovisualization Application Leveraging Aggregated Quantified-Self Data Jonathan K. Nelson Alan M. MacEachren The Pennsylvania State University The Pennsylvania State University [email protected] [email protected] Individual movement traces recorded by users of activity tracking applications such as Strava provide opportunities that extend beyond delivering personal value or insight to the individual who engages in these “quantified-self ” (QS) activ- ities. The large volumes of data generated by these individuals, when aggregated and anonymized, can be used by city planners, Departments of Transportation, advocacy groups, and researchers to help make cities safer and more efficient. This opportunity, however, is constrained by the technical skills and resources available to those tasked with assessing bi- cycling behavior in urban centers. This paper aims to address the question of how to design cartographic interfaces to serve as mediated platforms for making large amounts of individual bicycling data more accessible, usable, and actionable. Principles of cartographic representation, geovisual analytics techniques, and best practices in user interface/experience design are employed to arrive at an effective visualization tool for a broad urban planning audience. We use scenar- io-based design methods to encapsulate knowledge of map use practice gleaned from the development process, and conduct a post-implementation, two-part user study with seven domain experts to further assess the usability and utility of the interactive mapping tool. KEYWORDS: cartographic design study; user-centered design; movement data; quantified-self (QS); urban planning INTRODUCTION Advancements in global navigation satellite and air pollution exposure (Sun and Mobasheri 2017). and positioning systems, together with the subsequent Ubiquitous computing and Internet of Things (IoT) tech- increase in use of geo-enabled tracking devices, have re- nologies create further potential for integrating individual sulted in unprecedented amounts of individual movement movement data into smart city initiatives, such as traffic data (Swan 2012; Laube 2015). These data are increasing- congestion monitoring (Zanella et al. 2014). This can re- ly being generated using personal devices, such as smart- sult in a more humanized, bottom-up approach to city phones and other wearables (e.g., augmented eyewear, pe- planning (Smyth et al. 2013). The opportunity, however, dometers, smartwatches, textiles, wristbands, etc.). At the is constrained by the technical skills and resources avail- most ambitious end of the self-tracking spectrum is the able to those tasked with assessing bicyclist or pedestrian Quantified Self (QS) community, which is composed of behavior in urban centers. This paper aims to address the individuals who believe in “self-knowledge through num- question of how to design interactive mapping tools that can bers” and who use these devices to track biological, phys- help urban and transportation planners leverage personal fit- ical, behavioral, environmental, and/or other information ness data to better inform infrastructure decisions that aid in about themselves (Swan 2013). the safe and efficient movement of bicyclists? The movement data generated by quantified-selfers can More specifically, in this problem-driven research, we ex- offer more than just direct personal insight to the indi- amine the design of a commercial interactive cartographic vidual who engages in QS activities. The large volumes of application intended to support urban and regional plan- data generated by these individuals, when aggregated and ning. The interactive mapping tools considered in this de- anonymized, can also be used to inform city safety (Zeile sign study are focused on utilizing large volumes of indi- et al. 2015), preferential route choices (Baker et al. 2017), vidual movement data contributed voluntarily by users of © by the author(s). This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/4.0. Cartographic Perspectives, Number 96 User-centered Design and Evaluation of a Geovisualization Application… – Nelson & MacEachren 7 an activity tracking application, Strava. Metro is a small systems (GIS) or spatial analysis. However, the tool should division of Strava (the company, which shares a name with also support more advanced analysts, and offer immedi- its application) that aggregates and anonymizes data on ate insights into the fundamental tasks outlined above. bicycling activities recorded on the platform, and licens- A major contribution of our work is the methodological es these data to a variety of organizations that are taking framework we present for evaluating the extent to which data-driven approaches to city planning. Based on a needs the proposed design solution addresses the needs outlined assessment and work domain analysis carried out by the above. first author while employed by Strava, the following in- sights emerged: In the following sections, we first ground our design framework in relevant literature on cartographic approach- • There existed a disconnect between what Strava es to mapping movement, geovisual analytics techniques Metro assumed data users were capable of (in terms for interacting with complex representations of movement, of big data management, analysis, and visualization), and urban interfaces (or city dashboards). Next, we intro- and the reality of their time, resources, and abilities. duce Metro DataView, an interactive network flow map designed to make data on bicycle activity more accessible, • Data users faced significant challenges with data size/ usable, and useful to decision makers, stakeholders, and complexity, resulting in frustration, confusion, and researchers in the urban planning domain. A simplified limited ability to extract value from the data. approach to visualizing individual movement traces is then considered, followed by a presentation of a three-stage • Most data users aimed to accomplish some variant of user-centered design and evaluation model employed to the following tasks: quantify/qualify ridership; dis- both formatively and summatively assess the cartograph- tinguish between commute and recreational bicycling ic tools presented in this work. That model combines a corridors; and identify candidate areas for modifying hypothetical use case scenario and claims analysis with a or creating new bicycle facilities. post-implementation user study to (1) characterize the do- main problem, (2) synthesize knowledge of map use prac- Thus, we set out to develop a partnership with data users tice gleaned from the development process, (3) assess the to alleviate their frustration and help address their needs. extent to which the geovisualization tools support insight More specifically, we initiated a multi-year, user-centered discovery, and (4) evaluate interface usability and utility. design study to develop a geovisualization tool to make The paper concludes with a discussion of tool adoption and Metro data more accessible to stakeholders in the city impact, major contributions, design limitations, and op- planning process. These stakeholders may possess lim- portunities for future research and development. ited, or even no experience with geographic information BACKGROUND This section provides background on cartographic of a latitude/longitude coordinate pair and a timestamp. approaches relevant to mapping individual activity trac- Mapping these points directly is the simplest approach to es; highlights ongoing research in the geovisual analyt- visualizing and attempting to make sense of data in this ics community focused on exploring and making sense of form (Andrienko et al. 2008). Mapped depictions of raw complex movement data with an emphasis on transpor- GPS point data, however, become less feasible if the num- tation applications; and concludes with an overview on ber of trajectories is large, if they reveal personally iden- urban interfaces and their relevance to the visual commu- tifiable information, or if the analytical goal is to detect nication of movement for an urban planning audience. group—rather than individual—movement behavior. One, if not all, of these conditions will likely be met when CARTOGRAPHIC APPROACHES TO FLOW engaging with individual movement data. In these cases, MAPPING data aggregation becomes a viable strategy for preserving individual privacy while also making analytical tasks com- Individual movement data are commonly structured as putationally tractable and mapped results visually mean- series (or trajectories) of point records, each composed ingful (Rinzivillo et al. 2008). Cartographic Perspectives, Number 96 User-centered Design and Evaluation of a Geovisualization Application… – Nelson & MacEachren | 8 Approaches to representing the spatial flow of objects in Guo 2014), and to develop a multi-scale flow density esti- aggregate form have existed since at least 1845 (Robinson mation and selection methodology for visualizing patterns 1967). Effective flow maps are difficult to create, and have in complex OD pairs (Zhu et al. 2019). traditionally been drawn carefully by hand. Tobler (1987) introduced the challenges of migration flow mapping by Transportation, in particular, is an active research area in computer, and, despite decades of advancement