User interaction in visual analytic systems is critical to enabling visual data exploration. Through interacting with visualizations, users engage in sensemaking, a process of developing and understanding relationships within datasets through foraging and synthesis. For example, two-dimensional layouts of high-dimensional data can be generated by dimension reduction models, and provide users with an overview of the relationships between information. However, exploring such spatializations can require expertise with the internal mechanisms and parameters of these models. The core contribution of this work is semantic interaction, capable of steering such models without requiring expertise in dimension reduction models, but instead leveraging the domain expertise of the user. Semantic interaction infers the analytical reasoning of the user with model updates, steering the dimension reduction model for visual data exploration. As such, it is an approach to user interaction that leverages interactions designed for synthesis, and couples them with the underlying mathematical model to provide computational support for foraging. As a result, semantic interaction performs incremental model learning to enable synergy between the user's insights and the mathematical model. The contributions of this work are organized by providing a description of the principles of semantic interaction, providing design guidelines through the development of a visual analytic prototype, ForceSPIRE, and the evaluation of the impact of semantic interaction on the analytic process. The positive results of semantic interaction open a fundamentally new design space for designing user interactions in visual analytic systems. This research was funded in part by the National Science Foundation, CCF-0937071 and CCF-0937133, the Institute for Critical Technology and Applied Science at Virginia Tech, and the National Geospatial-Intelligence Agency contract #HMI1582-05-1-2001. / Ph. D.

The goal of this body of work is to explore various aspects of data analytics (DA) and its applications in agriculture. In our research, we produce decisions with mathematical models, create models, evaluate existing models, and review how certain models are best applied. The increasing granularity in decisions being made on farm, like individualized feeding, sub-plot level crop management, and plant and animal disease prevention, creates complex systems requiring DA to identify variance and patterns in data collected. Precision agriculture requires DA to make decisions about how to feasibly improve efficiency or performance in the system. Our research demonstrates ways to provide recommendations and make decisions in such systems. Our first research goal was to clarify research on the topic of endophyte-infected tall fescue by relating different infection-measuring techniques and quantifying the effect of infection-level on grazing cattle growth. Cattle graze endophyte-infected tall fescue in many parts of the U.S and this feedstuff is thought to limit growth performance in those cattle. Our results suggest ergovaline concentration makes up close to 80% of the effect of measured total ergot alkaloids and cattle average daily gain decreased 33 g/d for each 100ppb increase in ergovaline concentration. By comparing decreased weight gain to the costs of reseeding a pasture, producers can make decisions related to the management of infected pastures. The next research goal was to evaluate experimental and feed factors that affect measurements associated with ruminant protein digestion. Measurements explored were 0-h washout, potentially degradable, and undegradable protein fractions, protein degradation rate and digestibility of rumen undegradable protein. Our research found that the aforementioned measurements were significantly affected by feedstuff characteristics like neutral detergent fiber content and crude protein content, and also measurement variables like bag pore size, incubation time, bag area, and sample size to bag area ratio. Our findings suggest that current methods to measure and predict protein digestion lack robustness and are therefore not reliable to make feeding decisions or build research models. The first two research projects involved creating models to help researchers and farmers make better decisions. Next, we aimed to produce a summary of existing DA frameworks and propose future areas for model building in agriculture. Machine learning models were discussed along with potential applications in animal agriculture. Additionally, we discuss the importance of model evaluation when producing applicable models. We propose that the future of DA in agriculture comes with increasing decision making done without human input and better integration of DA insights into farmer decision-making. After detailing how mathematical models and machine learning could be used to further research, models were used to predict cases of clinical mastitis (CM) in dairy cows. Machine learning models took daily inputs relating to activity and production to produce probabilities of CM. By considering the economic costs of treatment and non-treatment in CM cases, we provide insight into the lack of applicable models being produced, and why smarter data collection, representative datasets, and validation that reflects how the model will be used are needed. The overall goal of this body of work was to advance our understanding of agriculture and the complex decisions involved through the use of DA. Each project sheds light on model building, model evaluation, or model applicability. By relating modeling techniques in other fields to agriculture, this research aims to improve translation of these techniques in future research. As data collection in agriculture becomes even more commonplace, the need for good modeling practices will increase. / Doctor of Philosophy / Data analytics (DA) has become more popular with the increasing data collection capabilities using technologies like sensors, improvement in data storage techniques, and expanding literature on algorithms that can be used in prediction and summarization. This body of work explores many aspects of agricultural DA and its applications on-farm. The field of precision agriculture has risen from an influx of data and new possibilities for using these data. Even small farms are now able to collect data using technologies like sensor-equipped tractors and drones which are relatively inexpensive. Our research shows how using mathematical models combined with these data can help researchers produce more applicable tools and, in turn, help producers make more targeted decisions. We examine cases where models improve the understanding of a system, specifically, the effect of endophyte infection in tall fescue pastures, the effect of measurement on protein digestibility for ration formulation, and methods to predict sparse diseases using big data. Although DA is widely applied, specific agricultural research on topics such as model types, model performance, and model utility needs to be done. This research presented herein expands on these topics in detail, using DA and mathematical models to make predictions and understand systems while utilizing applicable DA frameworks for future research.

Exploring coordinated relationships is an important task in data analytics. For example, an intelligence analyst may want to find three suspicious people who all visited the same four cities. However, existing techniques that display individual relationships, such as between lists of entities, require repetitious manual selection and significant mental aggregation in cluttered visualizations to find coordinated relationships. This work presents a visual analytics approach that applies biclusters to support coordinated relationships exploration. Each computed bicluster aggregates individual relationships into coordinated sets. Thus, coordinated relationships can be formalized as biclusters. However, how to incorporate biclusters into a visual analytics tool to support sensemaking tasks is challenging. To address this, this work features three key contributions: 1) a five-level design framework for bicluster visualizations, 2) BiSet, highlighting bicluster-based edge bundling, seriation-based multiple lists ordering, and interactions for dynamic information foraging and management, and 3) an evaluation of BiSet. / Ph. D.

Email correspondence has become the predominant method of communication for businesses. If not for the inherent privacy concerns, this electronically searchable data could be used to better understand how employees interact. After the Enron dataset was made available, researchers were able to provide great insight into employee behaviors based on the available data despite the many challenges with that dataset. The work in this thesis demonstrates a suite of methods to an appropriately anonymized academic email dataset created from volunteers' email metadata. This new dataset, from an internal email server, is first used to validate feature extraction and machine learning algorithms in order to generate insight into the interactions within the center. Based solely on email metadata, a random forest approach models behavior patterns and predicts employee job titles with $96%$ accuracy. This result represents classifier performance not only on participants in the study but also on other members of the center who were connected to participants through email. Furthermore, the data revealed relationships not present in the center's formal operating structure. The culmination of this work is an organic organizational chart, which contains a fuller understanding of the center's internal structure than can be found in the official organizational chart. / Master of Science

Big Data is transforming the way we live. From medical care to social networks, data is playing a central role in various applications. As the volume and dimensionality of datasets keeps growing, designing effective data analytics algorithms emerges as an important research topic in statistics. In this dissertation, I will summarize our research on two data analytics algorithms: a visual analytics algorithm named Grouped Observation Level Interaction with Multidimensional Scaling and a big data Monte Carlo sampling algorithm named Batched Permutation Sampler. These two algorithms are designed to enhance the capability of generating meaningful insights and utilizing massive datasets, respectively. / Ph. D.

Learning from text data often involves a loop of tasks that iterate between foraging for information and synthesizing it in incremental hypotheses. Past research has shown the advantages of using spatial workspaces as a means for synthesizing information through externalizing hypotheses and creating spatial schemas. However, spatializing the entirety of datasets becomes prohibitive as the number of documents available to the analysts grows, particularly when only a small subset are relevant to the tasks at hand. To address this issue, we developed the multi-model semantic interaction (MSI) technique, which leverages user interactions to aid in the display layout (as was seen in previous semantic interaction work), forage for new, relevant documents as implied by the interactions, and then place them in context of the user's existing spatial layout. This results in the ability for the user to conduct both implicit queries and traditional explicit searches. A comparative user study of StarSPIRE discovered that while adding implicit querying did not impact the quality of the foraging, it enabled users to 1) synthesize more information than users with only explicit querying, 2) externalize more hypotheses, 3) complete more synthesis-related semantic interactions. Also, 18% of relevant documents were found by implicitly generated queries when given the option. StarSPIRE has also been integrated with web-based search engines, allowing users to work across vastly different levels of data scale to complete exploratory data analysis tasks (e.g. literature review, investigative journalism). The core contribution of this work is multi-model semantic interaction (MSI) for usable big data analytics. This work has expanded the understanding of how user interactions can be interpreted and mapped to underlying models to steer multiple algorithms simultaneously and at varying levels of data scale. This is represented in an extendable multi-model semantic interaction pipeline. The lessons learned from this dissertation work can be applied to other visual analytics systems, promoting direct manipulation of the data in context of the visualization rather than tweaking algorithmic parameters and creating usable and intuitive interfaces for big data analytics. / Ph. D.

The current proliferation of connected displays and mobile devices from smart phones and tablets to wall-sized displays presents a number of exciting opportunities for information visualization and visual analytics. When a user employs heterogeneous displays collaboratively to achieve a goal, they form what is known as a display ecology. The display ecology enables multiple displays to function in concert within a broader technological environment to accomplish tasks and goals. However, since information and tasks are scattered and disconnected among separate displays, one of the inherent challenges associated with visual analysis in display ecologies is enabling users to seamlessly coordinate and subsequently connect and integrate information across displays. This research primarily addresses these challenges through the creation of interaction and visualization techniques and systems for display ecologies in order to support sensemaking with visual analysis. This dissertation explores essential visual analysis activities and design considerations for visual analysis in order to inform the new design of display ecologies for visual analysis. Based on identified design considerations, we then designed and developed two visual analysis systems. First, VisPorter supports intuitive gesture interactions for sharing and integrating information in a display ecology. Second, the Spatially Aware Visual Links (SAViL) presents a cross-display visual link technique capable of guiding the user's attention to relevant information across displays. It also enables the user to visually connect related information over displays in order to facilitate synthesizing information scattered over separate displays and devices. The various aspects associated with the techniques described herein help users to transform and empower the multiple displays in a display ecology for enhanced visual analysis and sensemaking. / Ph. D.

When exploring large, high-dimensional datasets, analysts often utilize two techniques for reducing the data to make exploration more tractable. The first technique, dimension reduction, reduces the high-dimensional dataset into a low-dimensional space while preserving high-dimensional structures. The second, clustering, groups similar observations while simultaneously separating dissimilar observations. Existing work presents a number of systems and approaches that utilize these techniques; however, these techniques can cooperate or conflict in unexpected ways. The core contribution of this work is the systematic examination of the design space at the intersection of dimension reduction and clustering when building intelligent, interactive tools in visual analytics. I survey existing techniques for dimension reduction and clustering algorithms in visual analytics tools, and I explore the design space for creating projections and interactions that include dimension reduction and clustering algorithms in the same visual interface. Further, I implement and evaluate three prototype tools that implement specific points within this design space. Finally, I run a cognitive study to understand how analysts perform dimension reduction (spatialization) and clustering (grouping) operations. Contributions of this work include surveys of existing techniques, three interactive tools and usage cases demonstrating their utility, design decisions for implementing future tools, and a presentation of complex human organizational behaviors. / Doctor of Philosophy / When an analyst is exploring a dataset, they seek to gain insight from the data. With data sets growing larger, analysts require techniques to help them reduce the size of the data while still maintaining its meaning. Two commonly-utilized techniques are dimension reduction and clustering. Dimension reduction seeks to eliminate unnecessary features from the data, reducing the number of columns to a smaller number. Clustering seeks to group similar objects together, reducing the number of rows to a smaller number. The contribution of this work is to explore how dimension reduction and clustering are currently being used in interactive visual analytics systems, as well as to explore how they could be used to address challenges faced by analysts in the future. To do so, I survey existing techniques and explore the design space for creating visualizations that incorporate both types of computations. I look at methods by which an analyst could interact with those projections in other to communicate their interests to the system, thereby producing visualizations that better match the needs of the analyst. I develop and evaluate three tools that incorporate both dimension reduction and clustering in separate computational pipelines. Finally, I conduct a cognitive study to better understand how users think about these operations, in order to create guidelines for better systems in the future.

Businesses have recognized that customers provide value to the firm beyond transactions, and leveraging this value through relationships in social media is a new area of interest for both academics and practitioners. Recent research has investigated how businesses can best manage their online presence on platforms not fully under their control, such as Facebook, YouTube, Instagram, TripAdvisor, and Yelp, among others. This dissertation extends the literature of customer engagement in social media through four contributions. First, we propose a framework that foregrounds the textual artifacts involved in online communication. Second, we develop a novel method for discovering the elements of successful Business to Customer (B2C) messages in online communities. Third, we propose a method, validated through experimentation, for finding critical product feedback in Customer to Customer (C2C) communications. Finally, we demonstrate that a set of novel numerical features can enhance the discovery of product defect mentions in C2C communications. We conclude by proposing a research agenda suggested by the framework that will further enhance our understanding of the complex customer interactions that characterize business in the era of social media. / Ph. D.

With the dramatic increase and continued growth of digital information, developing Visual Analytic systems that support human cognition and insight generation are more necessary than ever before, but there is currently no content-agnostic method for measuring or com- paring how well a system facilitates analysis. Researchers in industry and academia are developing advanced tools that offer automated data analysis combined with support for human sense-making; tools for a wide variety of sense-making tasks are freely available. Now, the pressing question is: which tool works best, and for what? We show that using Shannon's entropy and self-information measures will provide a measure of the complexity reduction that results from an analyst's actions while sorting the information. Further, we demonstrate that reduced complexity can be linked to the knowledge gained. This is important, because a metric for objectively evaluating the success of current systems in generating insights would establish a standard that future tools could build on. This work could help guide researchers and developers in making the next generation of analytic tools, and in the age of big data the effect of such tools could potentially impact everyone. / Master of Science