3,071 research outputs found
Algorithms, applications and systems towards interpretable pattern mining from multi-aspect data
How do humans move around in the urban space and how do they differ when the city undergoes terrorist attacks? How do users behave in Massive Open Online courses~(MOOCs) and how do they differ if some of them achieve certificates while some of them not? What areas in the court elite players, such as Stephen Curry, LeBron James, like to make their shots in the course of the game? How can we uncover the hidden habits that govern our online purchases? Are there unspoken agendas in how different states pass legislation of certain kinds? At the heart of these seemingly unconnected puzzles is this same mystery of multi-aspect mining, i.g., how can we mine and interpret the hidden pattern from a dataset that simultaneously reveals the associations, or changes of the associations, among various aspects of the data (e.g., a shot could be described with three aspects, player, time of the game, and area in the court)? Solving this problem could open gates to a deep understanding of underlying mechanisms for many real-world phenomena. While much of the research in multi-aspect mining contribute broad scope of innovations in the mining part, interpretation of patterns from the perspective of users (or domain experts) is often overlooked. Questions like what do they require for patterns, how good are the patterns, or how to read them, have barely been addressed. Without efficient and effective ways of involving users in the process of multi-aspect mining, the results are likely to lead to something difficult for them to comprehend.
This dissertation proposes the M^3 framework, which consists of multiplex pattern discovery, multifaceted pattern evaluation, and multipurpose pattern presentation, to tackle the challenges of multi-aspect pattern discovery. Based on this framework, we develop algorithms, applications, and analytic systems to enable interpretable pattern discovery from multi-aspect data. Following the concept of meaningful multiplex pattern discovery, we propose PairFac to close the gap between human information needs and naive mining optimization. We demonstrate its effectiveness in the context of impact discovery in the aftermath of urban disasters. We develop iDisc to target the crossing of multiplex pattern discovery with multifaceted pattern evaluation. iDisc meets the specific information need in understanding multi-level, contrastive behavior patterns. As an example, we use iDisc to predict student performance outcomes in Massive Open Online Courses given users' latent behaviors. FacIt is an interactive visual analytic system that sits at the intersection of all three components and enables for interpretable, fine-tunable, and scrutinizable pattern discovery from multi-aspect data. We demonstrate each work's significance and implications in its respective problem context. As a whole, this series of studies is an effort to instantiate the M^3 framework and push the field of multi-aspect mining towards a more human-centric process in real-world applications
Abstract visualization of large-scale time-varying data
The explosion of large-scale time-varying datasets has created critical challenges for scientists to study and digest. One core problem for visualization is to develop effective approaches that can be used to study various data features and temporal relationships among large-scale time-varying datasets.
In this dissertation, we first present two abstract visualization approaches to visualizing and analyzing time-varying datasets. The first approach visualizes time-varying datasets with succinct lines to represent temporal relationships of the datasets. A time line visualizes time steps as points and temporal sequence as a line. They are generated by sampling the distributions of virtual words across time to study temporal features. The key idea of time line is to encode various data properties with virtual words. We apply virtual words to characterize feature points and use their distribution statistics to measure temporal relationships. The second approach is ensemble visualization, which provides a highly abstract platform for visualizing an ensemble of datasets. Both approaches can be used for exploration, analysis, and demonstration purposes.
The second component of this dissertation is an animated visualization approach to study dramatic temporal changes. Animation has been widely used to show trends, dynamic features and transitions in scientific simulations, while animated visualization is new. We present an automatic animation generation approach that simulates the composition and transition of storytelling techniques and synthesizes animations to describe various event features. We also extend the concept of animated visualization to non-traditional time-varying datasets--network protocols--for visualizing key information in abstract sequences. We have evaluated the effectiveness of our animated visualization with a formal user study and demonstrated the advantages of animated visualization for studying time-varying datasets
Information Visualization and Visual Data Mining
Data visualization is the graphical display of abstract information for two purposes: sense-making (also called data analysis) and communication. Important stories live in our data and data visualization is a powerful means to discover and understand these stories, and then to present them to others. In this paper, we propose a classification of information visualization and visual data mining techniques which is based on the data type to be visualized, the visualization technique and the interaction and distortion technique. We exemplify the classification using a few examples, most of them referring to techniques and systems presented in this special issue
Multimodal Prediction based on Graph Representations
This paper proposes a learning model, based on rank-fusion graphs, for
general applicability in multimodal prediction tasks, such as multimodal
regression and image classification. Rank-fusion graphs encode information from
multiple descriptors and retrieval models, thus being able to capture
underlying relationships between modalities, samples, and the collection
itself. The solution is based on the encoding of multiple ranks for a query (or
test sample), defined according to different criteria, into a graph. Later, we
project the generated graph into an induced vector space, creating fusion
vectors, targeting broader generality and efficiency. A fusion vector estimator
is then built to infer whether a multimodal input object refers to a class or
not. Our method is capable of promoting a fusion model better than early-fusion
and late-fusion alternatives. Performed experiments in the context of multiple
multimodal and visual datasets, as well as several descriptors and retrieval
models, demonstrate that our learning model is highly effective for different
prediction scenarios involving visual, textual, and multimodal features,
yielding better effectiveness than state-of-the-art methods
Structuring visual exploratory analysis of skill demand
The analysis of increasingly large and diverse data for meaningful interpretation and question answering is handicapped by human cognitive limitations. Consequently, semi-automatic abstraction of complex data within structured information spaces becomes increasingly important, if its knowledge content is to support intuitive, exploratory discovery. Exploration of skill demand is an area where regularly updated, multi-dimensional data may be exploited to assess capability within the workforce to manage the demands of the modern, technology- and data-driven economy. The knowledge derived may be employed by skilled practitioners in defining career pathways, to identify where, when and how to update their skillsets in line with advancing technology and changing work demands. This same knowledge may also be used to identify the combination of skills essential in recruiting for new roles. To address the challenges inherent in exploring the complex, heterogeneous, dynamic data that feeds into such applications, we investigate the use of an ontology to guide structuring of the information space, to allow individuals and institutions to interactively explore and interpret the dynamic skill demand landscape for their specific needs. As a test case we consider the relatively new and highly dynamic field of Data Science, where insightful, exploratory data analysis and knowledge discovery are critical. We employ context-driven and task-centred scenarios to explore our research questions and guide iterative design, development and formative evaluation of our ontology-driven, visual exploratory discovery and analysis approach, to measure where it adds value to users’ analytical activity. Our findings reinforce the potential in our approach, and point us to future paths to build on
Exploratory search in time-oriented primary data
In a variety of research fields, primary data that describes scientific phenomena in an original condition is obtained.
Time-oriented primary data, in particular, is an indispensable data type, derived from complex measurements depending
on time. Today, time-oriented primary data is collected at rates that exceed the domain experts’ abilities to seek
valuable information undiscovered in the data. It is widely accepted that the magnitudes of uninvestigated data will
disclose tremendous knowledge in data-driven research, provided that domain experts are able to gain insight into the
data. Domain experts involved in data-driven research urgently require analytical capabilities. In scientific practice,
predominant activities are the generation and validation of hypotheses. In analytical terms, these activities are often
expressed in confirmatory and exploratory data analysis. Ideally, analytical support would combine the strengths of
both types of activities.
Exploratory search (ES) is a concept that seamlessly includes information-seeking behaviors ranging from search
to exploration. ES supports domain experts in both gaining an understanding of huge and potentially unknown data
collections and the drill-down to relevant subsets, e.g., to validate hypotheses. As such, ES combines predominant tasks
of domain experts applied to data-driven research. For the design of useful and usable ES systems (ESS), data scientists
have to incorporate different sources of knowledge and technology. Of particular importance is the state-of-the-art
in interactive data visualization and data analysis. Research in these factors is at heart of Information Visualization
(IV) and Visual Analytics (VA). Approaches in IV and VA provide meaningful visualization and interaction designs,
allowing domain experts to perform the information-seeking process in an effective and efficient way. Today, bestpractice
ESS almost exclusively exist for textual data content, e.g., put into practice in digital libraries to facilitate the
reuse of digital documents. For time-oriented primary data, ES mainly remains at a theoretical state.
Motivation and Problem Statement. This thesis is motivated by two main assumptions. First, we expect that
ES will have a tremendous impact on data-driven research for many research fields. In this thesis, we focus on
time-oriented primary data, as a complex and important data type for data-driven research. Second, we assume that
research conducted to IV and VA will particularly facilitate ES. For time-oriented primary data, however, novel
concepts and techniques are required that enhance the design and the application of ESS. In particular, we observe a
lack of methodological research in ESS for time-oriented primary data. In addition, the size, the complexity, and the
quality of time-oriented primary data hampers the content-based access, as well as the design of visual interfaces
for gaining an overview of the data content. Furthermore, the question arises how ESS can incorporate techniques
for seeking relations between data content and metadata to foster data-driven research. Overarching challenges for
data scientists are to create usable and useful designs, urgently requiring the involvement of the targeted user group
and support techniques for choosing meaningful algorithmic models and model parameters. Throughout this thesis,
we will resolve these challenges from conceptual, technical, and systemic perspectives. In turn, domain experts can
benefit from novel ESS as a powerful analytical support to conduct data-driven research.
Concepts for Exploratory Search Systems (Chapter 3). We postulate concepts for the ES in time-oriented primary
data. Based on a survey of analysis tasks supported in IV and VA research, we present a comprehensive selection of
tasks and techniques relevant for search and exploration activities. The assembly guides data scientists in the choice of
meaningful techniques presented in IV and VA. Furthermore, we present a reference workflow for the design and
the application of ESS for time-oriented primary data. The workflow divides the data processing and transformation
process into four steps, and thus divides the complexity of the design space into manageable parts. In addition, the
reference workflow describes how users can be involved in the design. The reference workflow is the framework for
the technical contributions of this thesis.
Visual-Interactive Preprocessing of Time-Oriented Primary Data (Chapter 4). We present a visual-interactive
system that enables users to construct workflows for preprocessing time-oriented primary data. In this way, we
introduce a means of providing content-based access. Based on a rich set of preprocessing routines, users can create
individual solutions for data cleansing, normalization, segmentation, and other preprocessing tasks. In addition, the
system supports the definition of time series descriptors and time series distance measures. Guidance concepts support
users in assessing the workflow generalizability, which is important for large data sets. The execution of the workflows
transforms time-oriented primary data into feature vectors, which can subsequently be used for downstream search
and exploration techniques. We demonstrate the applicability of the system in usage scenarios and case studies.
Content-Based Overviews (Chapter 5). We introduce novel guidelines and techniques for the design of contentbased
overviews. The three key factors are the creation of meaningful data aggregates, the visual mapping of these
aggregates into the visual space, and the view transformation providing layouts of these aggregates in the display
space. For each of these steps, we characterize important visualization and interaction design parameters allowing the
involvement of users. We introduce guidelines supporting data scientists in choosing meaningful solutions. In addition,
we present novel visual-interactive quality assessment techniques enhancing the choice of algorithmic model and
model parameters. Finally, we present visual interfaces enabling users to formulate visual queries of the time-oriented
data content. In this way, we provide means of combining content-based exploration with content-based search.
Relation Seeking Between Data Content and Metadata (Chapter 6). We present novel visual interfaces enabling
domain experts to seek relations between data content and metadata. These interfaces can be integrated into ESS
to bridge analytical gaps between the data content and attached metadata. In three different approaches, we focus
on different types of relations and define algorithmic support to guide users towards most interesting relations.
Furthermore, each of the three approaches comprises individual visualization and interaction designs, enabling users
to explore both the data and the relations in an efficient and effective way. We demonstrate the applicability of our
interfaces with usage scenarios, each conducted together with domain experts. The results confirm that our techniques
are beneficial for seeking relations between data content and metadata, particularly for data-centered research.
Case Studies - Exploratory Search Systems (Chapter 7). In two case studies, we put our concepts and techniques
into practice. We present two ESS constructed in design studies with real users, and real ES tasks, and real timeoriented
primary data collections. The web-based VisInfo ESS is a digital library system facilitating the visual access to
time-oriented primary data content. A content-based overview enables users to explore large collections of time series
measurements and serves as a baseline for content-based queries by example. In addition, VisInfo provides a visual
interface for querying time oriented data content by sketch. A result visualization combines different views of the data
content and metadata with faceted search functionality. The MotionExplorer ESS supports domain experts in human
motion analysis. Two content-based overviews enhance the exploration of large collections of human motion capture
data from two perspectives. MotionExplorer provides a search interface, allowing domain experts to query human
motion sequences by example. Retrieval results are depicted in a visual-interactive view enabling the exploration of
variations of human motions. Field study evaluations performed for both ESS confirm the applicability of the systems
in the environment of the involved user groups. The systems yield a significant improvement of both the effectiveness
and the efficiency in the day-to-day work of the domain experts. As such, both ESS demonstrate how large collections
of time-oriented primary data can be reused to enhance data-centered research.
In essence, our contributions cover the entire time series analysis process starting from accessing raw time-oriented
primary data, processing and transforming time series data, to visual-interactive analysis of time series. We present
visual search interfaces providing content-based access to time-oriented primary data. In a series of novel explorationsupport
techniques, we facilitate both gaining an overview of large and complex time-oriented primary data collections
and seeking relations between data content and metadata. Throughout this thesis, we introduce VA as a means of
designing effective and efficient visual-interactive systems. Our VA techniques empower data scientists to choose
appropriate models and model parameters, as well as to involve users in the design. With both principles, we support
the design of usable and useful interfaces which can be included into ESS. In this way, our contributions bridge the gap
between search systems requiring exploration support and exploratory data analysis systems requiring visual querying
capability. In the ESS presented in two case studies, we prove that our techniques and systems support data-driven
research in an efficient and effective way
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