AbstractInteractive history tools, ranging from basic undo and redo to branching timelines of user actions, facilitate iterative forms of interaction. In this paper, we investigate the design of history mechanisms for information visualization. We present a design space analysis of both architectural and interface issues, identifying design decisions and associated trade-offs. Based on this analysis, we contribute a design study of graphical history tools for Tableau, a database visualization system. These tools record and visualize interaction histories, support data analysis and communication of findings, and contribute novel mechanisms for presenting, managing, and exporting histories. Furthermore, we have analyzed aggregated collections of history sessions to evaluate Tableau usage. We describe additional tools for analyzing users history logs and how they have been applied to study usage patterns in Tableau. Index TermsVisualization, history, undo, analysis, presentation, evaluation. When investigating data with visualizations, users regularly traverse the space of views in an iterative fashion. Exploratory analysis may result in a number of hypotheses, leading to multiple rounds of question-answering. Analysts can generate unexpected questions that may be investigated immediately or revisited later. After conducting analysis, users may need to review, summarize, and communicate their findings, often in the form of reports or presentations. By surfacing users interaction history, we can facilitate analysis and communication. History mechanisms such as undo or timetravel enable revisitation in a variety of applications (e.g., [1-4, 6, 8, 12-14, 16-20, 22, 24-26]). As noted by Shneiderman [27], such history tools can play an important part in the visualization process, supporting iterative analysis by enabling users to review, retrieve, and revisit visualization states. Moreover, history tools can help users create reports or presentations, facilitating communication. Interaction histories can also benefit research and development. History log analysis of both individual and aggregate usage can identify common usage patterns and thereby assist usability evaluation. Researchers can also study interaction patterns to better understand and model analysts sense-making process [13] . However, the best history mechanisms for achieving these benefits are not always clear. Designers of visualization tools must consider a large design space of potential features and system architectures when designing history tools. These design decisions entail trade-offs in the types of history representations and operations that can be provided. For example, while it is easy to log low-level input events such as key presses and mouse clicks [25] , users can more readily take advantage of semantically meaningful models. Many operations might be performed on an interaction history, including editing, aggregation, bookmarking, annotation, and search. Architecture and interface design need to account for such operations. Furthermore, interaction histories can grow large quickly, and thus history mechanisms must scale accordingly. Scale concerns arise at the data level, where histories can benefit from compact description, and at the visual level, where history interfaces should be perceptually effective and space efficient. In this paper, we explore the design of graphical history tools to support visual analysis. We first present the results of a design space analysis, enumerating design decisions for the software architecture and graphical interface of history systems. Our analysis is intended to provide an overview of important design considerations and thereby help practitioners incorporate graphical history tools into their own visualization applications. Inspired by our design space analysis, we then present the design and implementation of graphical history tools to support analysis, communication, and evaluation in Tableau, a database visualization system [21, 28] . Although our primary contribution is a design study of history tools for visual analysis, our graphical history prototype also contributes new techniques for improving scalability, searching histories for relevant views, and generating presentations from history subsets. Furthermore, we have used our history model to support evaluation by analyzing recorded usage data. We describe our visual history analysis tools and how we have applied them to improve Tableaus user interface. We also calculate estimates of the impact of our history management techniques, finding that our techniques can reduce visualized history state spaces by over 60%. Architects of interactive history systems face a number of design decisions impacting the representations and operations available to users. To design our history tools, we first conducted a design space analysis to enumerate these decisions. We surveyed prior work spanning general history mechanisms [2, 8, 9, 23, 29] and interface designs in the areas of graphical design tools [8, 16, 17, 22, 26] , web browsing [1, 5, 12, 14, 15, 30] , and visualization and simulation [3, 4, 6, 10, 11, 13, 18, 19, 20, 24, 25] . In this section, we outline the design space of history tools using examples from this body of work.
Heer et al. REF present a design space analysis of history keeping systems.
Graphical Histories for Visualization: Supporting Analysis, Communication, and Evaluation
IEEE Transactions on Visualization and Computer Graphics
IEEE Transactions on Visualization and Computer Graphics
Computer Science Medicine