| 1. |
- Chatzimparmpas, Angelos, 1994-, et al.
(författare)
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A survey of surveys on the use of visualization for interpreting machine learning models
- 2020
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 19:3, s. 207-233
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Tidskriftsartikel (refereegranskat)abstract
- Research in machine learning has become very popular in recent years, with many types of models proposed to comprehend and predict patterns and trends in data originating from different domains. As these models get more and more complex, it also becomes harder for users to assess and trust their results, since their internal operations are mostly hidden in black boxes. The interpretation of machine learning models is currently a hot topic in the information visualization community, with results showing that insights from machine learning models can lead to better predictions and improve the trustworthiness of the results. Due to this, multiple (and extensive) survey articles have been published recently trying to summarize the high number of original research papers published on the topic. But there is not always a clear definition of what these surveys cover, what is the overlap between them, which types of machine learning models they deal with, or what exactly is the scenario that the readers will find in each of them. In this article, we present a metaanalysis (i.e. a ‘‘survey of surveys’’) of manually collected survey papers that refer to the visual interpretation of machine learning models, including the papers discussed in the selected surveys. The aim of our article is to serve both as a detailed summary and as a guide through this survey ecosystem by acquiring, cataloging, and presenting fundamental knowledge of the state of the art and research opportunities in the area. Our results confirm the increasing trend of interpreting machine learning with visualizations in the past years, and that visualization can assist in, for example, online training processes of deep learning models and enhancing trust into machine learning. However, the question of exactly how this assistance should take place is still considered as an open challenge of the visualization community.
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| 2. |
- Chatzimparmpas, Angelos, 1994-, et al.
(författare)
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VisRuler : Visual Analytics for Extracting Decision Rules from Bagged and Boosted Decision Trees
- 2023
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 22:2, s. 115-139
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Tidskriftsartikel (refereegranskat)abstract
- Bagging and boosting are two popular ensemble methods in machine learning (ML) that produce many individual decision trees. Due to the inherent ensemble characteristic of these methods, they typically outperform single decision trees or other ML models in predictive performance. However, numerous decision paths are generated for each decision tree, increasing the overall complexity of the model and hindering its use in domains that require trustworthy and explainable decisions, such as finance, social care, and health care. Thus, the interpretability of bagging and boosting algorithms—such as random forest and adaptive boosting—reduces as the number of decisions rises. In this paper, we propose a visual analytics tool that aims to assist users in extracting decisions from such ML models via a thorough visual inspection workflow that includes selecting a set of robust and diverse models (originating from different ensemble learning algorithms), choosing important features according to their global contribution, and deciding which decisions are essential for global explanation (or locally, for specific cases). The outcome is a final decision based on the class agreement of several models and the explored manual decisions exported by users. We evaluated the applicability and effectiveness of VisRuler via a use case, a usage scenario, and a user study. The evaluation revealed that most users managed to successfully use our system to explore decision rules visually, performing the proposed tasks and answering the given questions in a satisfying way.
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| 3. |
- Coimbra, Danilo B., et al.
(författare)
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Explaining three-dimensional dimensionality reduction plots
- 2016
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 15:2, s. 154-172
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Tidskriftsartikel (refereegranskat)abstract
- Understanding three-dimensional projections created by dimensionality reduction from high-variate datasets is very challenging. In particular, classical three-dimensional scatterplots used to display such projections do not explicitly show the relations between the projected points, the viewpoint used to visualize the projection, and the original data variables. To explore and explain such relations, we propose a set of interactive visualization techniques. First, we adapt and enhance biplots to show the data variables in the projected threedimensional space. Next, we use a set of interactive bar chart legends to show variables that are visible from a given viewpoint and also assist users to select an optimal viewpoint to examine a desired set of variables. Finally, we propose an interactive viewpoint legend that provides an overview of the information visible in a given three-dimensional projection from all possible viewpoints. Our techniques are simple to implement and can be applied to any dimensionality reduction technique. We demonstrate our techniques on the exploration of several real-world high-dimensional datasets.
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| 4. |
- Einsfeld, Katja, et al.
(författare)
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Knowledge Generation Through Human-Centered Information Visualization
- 2009
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Ingår i: Information Visualization. - : Palgrave Macmillan Ltd. - 1473-8716 .- 1473-8724. ; 8:3, s. 180-196
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Tidskriftsartikel (refereegranskat)abstract
- One important intention of human-centered information visualization is to represent huge amounts of abstract data in a visual representation that allows even users from foreign application domains to interact with the visualization, to understand the underlying data, and finally, to gain new, application-related knowledge. The visualization will help experts as well as non-experts to link previously or isolated knowledge-items in their mental map with new insights.Our approach explicitly supports the process of linking knowledge-items with three concepts. At first, the representation of data items in an ontology categorizes and relates them. Secondly, the use of various visualization techniques visually correlates isolated items by graph-structures, layout, attachment, integration, or hyperlink techniques. Thirdly, the intensive use of visual metaphors relates a known source domain to a less known target domain. In order to realize a scenario of these concepts, we developed a visual interface for non-experts to maintain complex wastewater treatment plants. This domain-specific application is used to give our concepts a meaningful background.
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| 5. |
- Elmqvist, Niklas, 1977, et al.
(författare)
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CiteWiz: a tool for the visualization of scientific citation networks
- 2007
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Ingår i: Information Visualization. - 1473-8716 .- 1473-8724. ; 6:3, s. 215-232
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Tidskriftsartikel (refereegranskat)abstract
- We present CiteWiz, an extensible framework for visualization of scientific citation networks. The system is based on a taxonomy of citation database usage for researchers, and provides a timeline visualization for overviews and an influence visualization for detailed views. The timeline displays the general chronology and importance of authors and articles in a citation database, whereas the influence visualization is implemented using the Growing Polygons technique, suitably modified to the context of browsing citation data. Using the latter technique, hierarchies of articles with potentially very long citation chains can be graphically represented. The visualization is augmented with mechanisms for parent–child visualization and suitable interaction techniques for interacting with the view hierarchy and the individual articles in the dataset. We also provide an interactive concept map for keywords and co-authorship using a basic force-directed graph layout scheme. A formal user study indicates that CiteWiz is significantly more efficient than traditional database interfaces for high-level analysis tasks relating to influence and overviews, and equally efficient for low-level tasks such as finding a paper and correlating bibliographical data.
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| 6. |
- Elmqvist, Niklas, 1977, et al.
(författare)
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DataMeadow: a visual canvas for analysis of large-scale multivariate data
- 2008
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 7:1, s. 18-33
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Tidskriftsartikel (refereegranskat)abstract
- Supporting visual analytics of multiple large-scale multidimensional data sets requires a high degree of interactivity and user control beyond the conventional challenges of visualizing such data sets. We present the DataMeadow, a visual canvas providing rich interaction for constructing visual queries using graphical set representations called DataRoses. A DataRose is essentially a starplot of selected columns in a data set displayed as multivariate visualizations with dynamic query sliders integrated into each axis. The purpose of the DataMeadow is to allow users to create advanced visual queries by iteratively selecting and filtering into the multidimensional data. Furthermore, the canvas provides a clear history of the analysis that can be annotated to facilitate dissemination of analytical results to stakeholders. A powerful direct manipulation interface allows for selection, filtering, and creation of sets, subsets, and data dependencies. We have evaluated our system using a qualitative expert review involving two visualization researchers. Results from this review are favorable for the new method.
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| 7. |
- Elmqvist, Niklas, et al.
(författare)
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Fluid Interaction for Information Visualization
- 2011
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 10:4, s. 327-340
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Tidskriftsartikel (refereegranskat)abstract
- Despite typically receiving little emphasis in visualization research, interaction in visualization is the catalyst for the user’s dialogue with the data, and, ultimately, the user’s actual understanding and insight into these data. There are many possible reasons for this skewed balance between the visual and interactive aspects of a visualization. One reason is that interaction is an intangible concept that is difficult to design, quantify, and evaluate. Unlike for visual design, there are few examples that show visualization practitioners and researchers how to design the interaction for a new visualization in the best manner. In this article, we attempt to address this issue by collecting examples of visualizations with ‘best-in-class’ interaction and using them to extract practical design guidelines for future designers and researchers. We call this concept fluid interaction, and we propose an operational definition in terms of the direct manipulation and embodied interaction paradigms, the psychological concept of ‘flow’, and Norman’s gulfs of execution and evaluation.
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| 8. |
- Forsell, C., et al.
(författare)
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Surface Glyphs for Efficient Visualization of Multivariate Data
- 2006
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Ingår i: Information Visualization. - 1473-8716 .- 1473-8724. ; 5:2, s. 112-124
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Tidskriftsartikel (refereegranskat)abstract
- We present a first effort to evaluate the possible utility of a new type of surface glyphs intended for visualizations of multivariate spatial data. The glyphs are based on results from vision research suggesting that our perception of metric 3D structure is distorted and imprecise relative to the actual scene before us; only a class of qualitative properties of the scene is perceived with accuracy. These properties are best characterized as being invariant over affine but not Euclidean transformations. A large number of possible 3D glyphs for the visualization of spatial data can be constructed using such properties. One group of such glyphs is based on the local sign of surface curvature. We investigated this group in two visualization experiments. The results show that available sources of 3D structural information were sufficient for our subjects to make fast and accurate judgments. Some implications for visualization are also discussed.
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| 9. |
- Forsén, Gunnar, et al.
(författare)
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Pinpoint : A design study in interactive visualization for finding people in a large organization
- 2009
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Ingår i: Information Visualization. - : Palgrave Macmillan. - 1473-8716 .- 1473-8724. ; 9, s. 141-151
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Tidskriftsartikel (refereegranskat)abstract
- This design study reports on how information visualization was applied to the common problem for knowledge workers to find people with relevant expertise and interests in a large organization. The outcome is the Pinpoint concept, an interactive visualization where the user's most closely related colleagues are presented radially for browsing, filtering and further exploration of the topical networks of the organization. Based on design reasoning and empirical validation, we claim that the concept approaches desirability as well as usefulness and usability in its intended use situation. We further argue that it is feasible for deployment under certain conditions, and that it is applicable in a range of large organizations if organization-specific policies and standards are taken into account.
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| 10. |
- Gleicher, Michael, et al.
(författare)
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Visual Comparison for Information Visualization
- 2011
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 10:5-4, s. 289-309
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Tidskriftsartikel (refereegranskat)abstract
- Data analysis often involves the comparison of complex objects. With the ever increasing amounts and complexity of data, the demand for systems to help with these comparisons is also growing. Increasingly, information visualization tools support such comparisons explicitly, beyond simply allowing a viewer to examine each object individually. In this paper, we argue that the design of information visualizations of complex objects can, and should, be studied in general, that is independently of what those objects are. As a first step in developing this general understanding of comparison, we propose a general taxonomy of visual designs for comparison that groups designs into three basic categories, which can be combined. To clarify the taxonomy and validate its completeness, we provide a survey of work in information visualization related to comparison. Although we find a great diversity of systems and approaches, we see that all designs are assembled from the building blocks of juxtaposition, superposition and explicit encodings. This initial exploration shows the power of our model, and suggests future challenges in developing a general understanding of comparative visualization and facilitating the development of more comparative visualization tools.
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| 11. |
- Ho, Quan, 1975-, et al.
(författare)
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A Web-Enabled Visualization Toolkit for Geovisual Analytics
- 2012
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 11:1, s. 22-42
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Tidskriftsartikel (refereegranskat)abstract
- A framework and class library (GAV Flash) implemented in Adobe’s ActionScript is introduced, designed with the intention to significantly shorten the time and effort needed to develop customized web-enabled applications for geovisual analytics tasks. Through an atomic layered component architecture, GAV Flash provides a collection of interactive geo- and information visualization representations for exploring high dimensional spaces and extended with motion behavior. Versatile interaction methods are drawn from many data visualization research areas and optimized for dynamic web visualization of spatio-temporal and multivariate data. Based on layered component thinking and the use of programming interface mechanism the GAV Flash architecture is open and facilitates the creation of new or improved versions of existing components so that ideas can be tried out or optimized rapidly in a fully functional environment. Not only is GAV Flash a tool for interactive visualization but also supports storytelling around visual analytics in which visual representations not only serve as a discovery tool for individuals but also as a mean to share stories among users fostering a social style of collaborative data analysis. A mechanism “snapshot” for saving the explorative results of a reasoning process is introduced that aids collaboration and publication of gained insight and knowledge embedded as dynamic visualizations in blogs or web pages with associative metadata or “storytelling”.
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| 12. |
- Isenberg, Petra, et al.
(författare)
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Collaborative Visualization: Definition, Challenges, and Research Agenda
- 2011
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 10:4, s. 310-326
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Tidskriftsartikel (refereegranskat)abstract
- The conflux of two growing areas of technology – collaboration and visualization – into a new research direction, collaborative visualization, provides new research challenges. Technology now allows us to easily connect and collaborate with one another – in settings as diverse as over networked computers, across mobile devices, or using shared displays such as interactive walls and tabletop surfaces. Digital information is now regularly accessed by multiple people in order to share information, to view it together, to analyze it, or to form decisions. Visualizations are used to deal more effectively with large amounts of information while interactive visualizations allow users to explore the underlying data. While researchers face many challenges in collaboration and in visualization, the emergence of collaborative visualization poses additional challenges, but it is also an exciting opportunity to reach new audiences and applications for visualization tools and techniques.The purpose of this article is (1) to provide a definition, clear scope, and overview of the evolving field of collaborative visualization, (2) to help pinpoint the unique focus of collaborative visualization with its specific aspects, challenges, and requirements within the intersection of general computer-supported cooperative work and visualization research, and (3) to draw attention to important future research questions to be addressed by the community. We conclude by discussing a research agenda for future work on collaborative visualization and urge for a new generation of visualization tools that are designed with collaboration in mind from their very inception.
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| 13. |
- Johansson Fernstad, Sara, et al.
(författare)
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Quality Based Guidance for Exploratory Dimensionality Reduction
- 2013
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Ingår i: Information Visualization. - : Palgrave Macmillan / SAGE Publications (UK and US). - 1473-8716 .- 1473-8724. ; 12:1, s. 44-64
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Tidskriftsartikel (refereegranskat)abstract
- High dimensional data sets containing hundreds of variables are difficult to explore, since traditional visualization methods often are unable to represent such data effectively. Dimensionality reduction is commonly employed prior to visualization to address this difficulty, and numerous dimensionality reduction methods are available. However, few dimensionality reduction approaches take the importance of several structures into account and few provide an overview of structures existing in the full high dimensional data set. For exploratory analysis, as well as for many other tasks, several structures may be of interest and exploration of the full high dimensional data set without reduction may also be desirable.This paper presents methods for exploratory analysis and interactive dimensionality reduction, where automated methods are employed to analyse and rank the variables using a range of quality metrics, providing one or more measures of ‘interestingness’ for individual variables. Through ranking, a single value of interestingness is obtained based on several quality metrics which is usable as a threshold for the most interesting variables. An interactive environment is presented where the user is provided many possibilities to explore and gain understanding of the structures within the high dimensional data set, all based on quality metrics and ranking. Guided by this, the analyst can explore the high dimensional data set and select interactively a subset of the potentially most interesting variables, employing various interactive methods for dimensionality reduction. The effectiveness and usefulness of the system is demonstrated through a use-case analysing data from a DNA sequence-based study of bacterial populations.
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| 14. |
- Johansson, Jimmy, et al.
(författare)
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On the usability of three-dimensional display in parallel coordinates: Evaluating the efficiency of identifying two-dimensional relationships
- 2014
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 13:1, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, several different attempts have been made to extend the well-known technique of parallel coordinates using a three-dimensional display. This article presents an evaluation that investigates the performance of the three-dimensional parallel coordinates technique and compares it with standard, two-dimensional parallel coordinates for analysis of two-dimensional relationships. Three-dimensional parallel coordinates, based on parallel planes instead of parallel axes, have been used for many years within the information visualization community for a variety of applications. Despite its quite common use, no formal evaluation detailing its usefulness for different tasks has been conducted. The evaluation presented in this article is the first step towards determining the usefulness of this type of three-dimensional parallel coordinates. The study compared three-dimensional parallel coordinates, using two different axis configurations commonly seen in the literature, with standard two-dimensional parallel coordinates for identification of two-dimensional relationships between variables in multivariate data. This type of task and the relationships to be judged are known to be well supported by two-dimensional parallel coordinates and multi-relational three-dimensional parallel coordinates. The results show that for identification of two-dimensional relationships, two-dimensional parallel coordinates are superior to the three-dimensional extensions, in terms of both response time and accuracy. Subjective opinions were also in favour of two-dimensional parallel coordinates. This study adds to the much-needed body of work examining the usability of three-dimensional representations in information visualization and for what tasks and data a proposed method is or is not appropriate.
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| 15. |
- Johansson, Jimmy, et al.
(författare)
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Perceiving patterns in parallel coordinates: determining thresholds for identification of relationships
- 2008
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Ingår i: Information Visualization. - : Palgrave macmillan. - 1473-8716 .- 1473-8724. ; 7:2, s. 152-162
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Tidskriftsartikel (refereegranskat)abstract
- This article presents a study that investigates the ability of humans to perceive relationships (patterns) in parallel coordinates, an ability that is crucial to the use of this popular visualization technique. It introduces a visual quality metric, acceptable distortions of patterns, which establishes the level of noise that may be present in data while allowing accurate identification of patterns. This metric was used to assess perceptual performance of standard 2D parallel coordinates and multi-relational 3D parallel coordinates in two experiments. In multi-relational 3D parallel coordinates the axes are placed on a circle with a focus axis in the centre, allowing a simultaneous analysis between the focus variable and all other variables. The experiments aimed to determine the maximum number of variables that can be, from a user's point of view, efficiently used in a multi-relational 3D parallel coordinates display and to present a first attempt to study users' ability to analyse noisy data in parallel coordinates. The results show that, in terms of the acceptable level of noise in data, a multi-relational 3D parallel coordinates visualization having 11 axes (variables) is as efficient as standard 2D parallel coordinates. Visualizing a larger number of variables would possibly require a greater amount of manipulation of the visualization and thus be less efficient.
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| 16. |
- Johansson, Jimmy, et al.
(författare)
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Revealing Structure in Visualizations of Dense 2D and 3D Parallel Coordinates
- 2006
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 5:2, s. 125-136
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Tidskriftsartikel (refereegranskat)abstract
- Parallel coordinates is a well-known technique used for visualization of multivariate data. When the size of the data sets increases the parallel coordinates display results in an image far too cluttered to perceive any structure. We tackle this problem by constructing high-precision textures to represent the data. By using transfer functions that operate on the high-precision textures, it is possible to highlight different aspects of the entire data set or clusters of the data. Our methods are implemented in both standard 2D parallel coordinates and 3D multi-relational parallel coordinates. Furthermore, when visualizing a larger number of clusters, a technique called 'feature animation' may be used as guidance by presenting various cluster statistics. A case study is also performed to illustrate the analysis process when analysing large multivariate data sets using our proposed techniques.
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| 17. |
- Jusufi, Ilir, 1983-, et al.
(författare)
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Exploring Biological Data : Mappings between Ontology- and Cluster-based Representations
- 2013
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 12:3-4, s. 291-307
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Tidskriftsartikel (refereegranskat)abstract
- Ontologies and hierarchical clustering are both important tools in biology and medicineto study high-throughput data such as transcriptomics and metabolomics data. Enrichmentof ontology terms in the data is used to identify statistically overrepresented ontology terms,giving insight into relevant biological processes or functional modules. Hierarchical clusteringis a standard method to analyze and visualize data to find relatively homogeneousclusters of experimental data points. Both methods support the analysis of the same dataset, but are usually considered independently. However, often a combined view is desired:visualizing a large data set in the context of an ontology under consideration of a clusteringof the data. This article proposes new visualization methods for this task. They allow forinteractive selection and navigation to explore the data under consideration as well as visualanalysis of mappings between ontology- and cluster-based space-filling representations. Inthis context, we discuss our approach together with specific properties of the biological inputdata and identify features that make our approach easily usable for domain experts.
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| 18. |
- Jusufi, Ilir, 1983-, et al.
(författare)
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Guiding the Interactive Exploration of Metabolic Pathway Interconnections
- 2012
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 11:2, s. 136-150
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Tidskriftsartikel (refereegranskat)abstract
- Approaches to investigate biological processes have been of strong interest in the past few years and are thefocus of several research areas, especially Systems Biology. Biochemical networks as representations ofprocesses are very important for a comprehensive understanding of living beings. Drawings of these networksare often visually overloaded and do not scale. A common solution to deal with this complexity is to divide thecomplete network, for example, the metabolism, into a large set of single pathways that are hierarchicallystructured. If those pathways are visualized, this strategy generates additional navigation and explorationproblems as the user loses the context within the complete network.In this article, we present a general solution to this problem of visualizing interconnected pathways anddiscuss it in context of biochemical networks. Our new visualization approach supports the analyst in obtainingan overview to related pathways if they are working within a particular pathway of interest. By usingglyphs, brushing, and topological information of the related pathways, our interactive visualization is ableto intuitively guide the exploration and navigation process, and thus the analysis processes too. To deal withreal data and current networks, our tool has been implemented as a plugin for the VANTED system.
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| 19. |
- Kerren, Andreas, et al.
(författare)
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Workshop Report: Information Visualization : Human-Centered Issues in Visual Representation, Interaction, and Evaluation
- 2007
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Ingår i: Information Visualization. - : Palgrave Macmillan Ltd. - 1473-8724 .- 1473-8716. ; 6:3, s. 189-196
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Tidskriftsartikel (refereegranskat)abstract
- From 28 May to 1 June 2007, a seminar on 'Information Visualization–Human-Centered Issues in Visual Representation, Interaction, and Evaluation' took place at the International Conference and Research Center for Computer Science, Dagstuhl Castle, Germany. One important aim of this seminar was to bring together researchers and practitioners from Information Visualization and related fields, as well as from application areas, for lively discussion and interaction. The seminar allowed critical reflection on actual research efforts, the state of field, evaluation challenges, and other important topics. This report summarizes the event.
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| 20. |
- Kjellin, Andreas, et al.
(författare)
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Different levels of 3D : An evaluation of visualized discrete spatiotemporal data in space-time cubes
- 2010
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 9:2, s. 152-164
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Tidskriftsartikel (refereegranskat)abstract
- New technologies and techniques allow novel kinds of visualizations and different types of 3D visualizations are constantly developed. We propose a categorization of 3D visualizations and, based on this categorization, evaluate two versions of a space-time cube that show discrete spatiotemporal data. The two visualization techniques used are a head-tracked stereoscopic visualization (‘strong 3D’) and a static monocular visualization (‘weak 3D’). In terms of effectiveness and efficiency the weak 3D visualization is as good as the strong 3D and thus the need for advanced 3D visualizations in these kinds of tasks may not be necessary.
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| 21. |
- Kucher, Kostiantyn, et al.
(författare)
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Visual Analysis of Online Social Media to Open Up the Investigation of Stance Phenomena
- 2016
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 15:2, s. 93-116
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Tidskriftsartikel (refereegranskat)abstract
- Online social media are a perfect text source for stance analysis. Stance in human communication is concerned with speaker attitudes, beliefs, feelings and opinions. Expressions of stance are associated with the speakers' view of what they are talking about and what is up for discussion and negotiation in the intersubjective exchange. Taking stance is thus crucial for the social construction of meaning. Increased knowledge of stance can be useful for many application fields such as business intelligence, security analytics, or social media monitoring. In order to process large amounts of text data for stance analyses, linguists need interactive tools to explore the textual sources as well as the processed data based on computational linguistics techniques. Both original texts and derived data are important for refining the analyses iteratively. In this work, we present a visual analytics tool for online social media text data that can be used to open up the investigation of stance phenomena. Our approach complements traditional linguistic analysis techniques and is based on the analysis of utterances associated with two stance categories: sentiment and certainty. Our contributions include (1) the description of a novel web-based solution for analyzing the use and patterns of stance meanings and expressions in human communication over time; and (2) specialized techniques used for visualizing analysis provenance and corpus overview/navigation. We demonstrate our approach by means of text media on a highly controversial scandal with regard to expressions of anger and provide an expert review from linguists who have been using our tool.
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| 22. |
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| 23. |
- Skeppstedt, Maria, et al.
(författare)
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From word clouds to Word Rain: Revisiting the classic word cloud to visualize climate change texts
- 2024
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 23:3, s. 217-238
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Tidskriftsartikel (refereegranskat)abstract
- Word Rain is a development of the classic word cloud. It addresses some of the limitations of word clouds, in particular the lack of a semantically motivated positioning of the words, and the use of font size as a sole indicator of word prominence. Word Rain uses the semantic information encoded in a distributional semantics-based language model – reduced into one dimension – to position the words along the x-axis. Thereby, the horizontal positioning of the words reflects semantic similarity. Font size is still used to signal word prominence, but this signal is supplemented with a bar chart, as well as with the position of the words on the y-axis. We exemplify the use of Word Rain by three concrete visualization tasks, applied on different real-world texts and document collections on climate change. In these case studies, word2vec models, reduced to one dimension with t-SNE, are used to encode semantic similarity, and TF-IDF is used for measuring word prominence. We evaluate the technique further by carrying out domain expert reviews.
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| 24. |
- Ventocilla, Elio, 1984-, et al.
(författare)
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A comparative user study of visualization techniques for cluster analysis of multidimensional data sets
- 2020
-
Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 19:4, s. 318-338
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Tidskriftsartikel (refereegranskat)abstract
- This article presents an empirical user study that compares eight multidimensional projection techniques for supporting the estimation of the number of clusters, ?, embedded in six multidimensional data sets. The selection of the techniques was based on their intended design, or use, for visually encoding data structures, that is, neighborhood relations between data points or groups of data points in a data set. Concretely, we study: the difference between the estimates of ? as given by participants when using different multidimensional projections; the accuracy of user estimations with respect to the number of labels in the data sets; the perceived usability of each multidimensional projection; whether user estimates disagree with ? values given by a set of cluster quality measures; and whether there is a difference between experienced and novice users in terms of estimates and perceived usability. The results show that: dendrograms (from Ward’s hierarchical clustering) are likely to lead to estimates of ? that are different from those given with other multidimensional projections, while Star Coordinates and Radial Visualizations are likely to lead to similar estimates; t-Stochastic Neighbor Embedding is likely to lead to estimates which are closer to the number of labels in a data set; cluster quality measures are likely to produce estimates which are different from those given by users using Ward and t-Stochastic Neighbor Embedding; U-Matrices and reachability plots will likely have a low perceived usability; and there is no statistically significant difference between the answers of experienced and novice users. Moreover, as data dimensionality increases, cluster quality measures are likely to produce estimates which are different from those perceived by users using any of the assessed multidimensional projections. It is also apparent that the inherent complexity of a data set, as well as the capability of each visual technique to disclose such complexity, has an influence on the perceived usability.
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| 25. |
- Vrotsou, Katerina, 1980-, et al.
(författare)
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2D and 3D Representations for Feature Recognition in Time Geographical Diary Data
- 2010
-
Ingår i: Information Visualization. - : Palgrave Macmillan Ltd. - 1473-8716 .- 1473-8724. ; 9:4, s. 263-276
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Tidskriftsartikel (refereegranskat)abstract
- Time geographical representations are becoming a common approach to analysing spatio-temporal data. Such representations appear intuitive in the process of identifying patterns and features as paths of populations form tracks through the 3D space, which can be seen converging and diverging over time. In this article, we compare 2D and 3D representations within a time geographical visual analysis tool for activity diary data. We identify a representative task and evaluate task performance between the two representations. The results show that the 3D representation has benefits over the 2D representation for feature identification but also indicate that these benefits can be lost if the 3D representation is not carefully constructed to help the user to see them.
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| 26. |
- Vrotsou, Katerina, et al.
(författare)
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Are we what we do? Exploring group behaviour through user-defined event-sequence similarity
- 2014
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 13:3, s. 232-247
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Tidskriftsartikel (refereegranskat)abstract
- The study of human activity in space and time is an inherent part of human geography. In order to perform such studies, data on the time use of individuals, in terms of sequence and timing of performed activities, are collected and analysed. A common assumption when analysing individuals’ time use is that groups that exhibit similar background and demographic characteristics also display similarities in how they use their time to structure their daily lives. In this article, we set out to investigate the correctness of such assumptions. We propose a visual analytics process based on sequence similarity measures tailored to event-based data such as performed activity sequences. The process allows an analyst to retrieve similarly behaving records according to user-selected similarity preferences and interactively explore aspects of this similarity in a multiple linked-view environment.
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| 27. |
- Winkler Pettersson, Lars, et al.
(författare)
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On the role of visual references in collaborative visualization
- 2010
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Ingår i: Information Visualization. - : SAGE Publications. - 1473-8716 .- 1473-8724. ; 9:2, s. 98-114
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Tidskriftsartikel (refereegranskat)abstract
- Multi-Viewer Display Environments (MVDE) provide unique opportunities to present personalized information to several users concurrently in the same physical display space. MVDEs can support correct 3D visualizations to multiple users, present correctly oriented text and symbols to all viewers and allow individually chosen subsets of information in a shared context. MVDEs aim at supporting collaborative visual analysis, and when used to visualize disjoint information in partitioned visualizations they even necessitate collaboration. When solving visual tasks collaboratively in a MVDE, overall performance is affected not only by the inherent effects of the graphical presentation but also by the interaction between the collaborating users. We present results from an empirical study where we compared views with lack of shared visual references in disjoint sets of information to views with mutually shared information. Potential benefits of 2D and 3D visualizations in a collaborative task were investigated and the effects of partitioning visualizations both in terms of task performance, interaction behavior and clutter reduction. In our study of a collaborative task that required only a minimum of information to be shared, we found that partitioned views with a lack of shared visual references were significantly less efficient than integrated views. However, the study showed that subjects were equally capable of solving the task at low error levels in partitioned and integrated views. An explorative analysis revealed that the amount of visual clutter was reduced heavily in partitioned visualization, whereas verbal and deictic communication between subjects increased. It also showed that the type of the visualization (2D/3D) affects interaction behavior strongly. An interesting result is that collaboration on complex geo-time visualizations is actually as efficient in 2D as in 3D.
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| 28. |
- Witschard, Daniel, et al.
(författare)
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Interactive Optimization of Embedding-based Text Similarity Calculations
- 2022
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 21:4, s. 335-353
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Tidskriftsartikel (refereegranskat)abstract
- Comparing text documents is an essential task for a variety of applications within diverse research fields, and several different methods have been developed for this. However, calculating text similarity is an ambiguous and context-dependent task, so many open challenges still exist. In this paper, we present a novel method for text similarity calculations based on the combination of embedding technology and ensemble methods. By using several embeddings, instead of only one, we show that it is possible to achieve higher quality, which in turn is a key factor for developing high-performing applications for text similarity exploitation. We also provide a prototype visual analytics tool which helps the analyst to find optimal performing ensembles and gain insights to the inner workings of the similarity calculations. Furthermore, we discuss the generalizability of our key ideas to fields beyond the scope of text analysis.
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| 29. |
- Forsell, Camilla, et al.
(författare)
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Surface Glyphs for Efficient Visualization of Spatial Multivariate Data
- 2006
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Ingår i: Information Visualization. - 1473-8716. ; 5, s. 112-124
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Tidskriftsartikel (refereegranskat)abstract
- We present a first effort to evaluate the possible utility of a new type of surface glyphs intended for visualizations of multivariate spatial data. The glyphs are based on results from vision research suggesting that our perception of metric 3D structure is distorted and imprecise relative to the actual scene before us; only a class of qualitative properties of the scene is perceived with accuracy. These properties are best characterized as being invariant over affine but not Euclidean transformations. A large number of possible 3D glyphs for the visualization of spatial data can be constructed using such properties. One group is based on the local sign of surface curvature. We investigated these properties in two visualization experiments. The results show that available sources of 3D structural information were sufficient for our subjects to make fast and accurate judgments. Some implications for visualization are discussed.
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| 30. |
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| 31. |
- Lind, Mats, et al.
(författare)
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Metric structure in visualization
- 2003
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Ingår i: Information Visualization. - 1473-8716. ; 2, s. 51-57
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Tidskriftsartikel (refereegranskat)
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