Topic modeling is an effective tool for analyzing the thematic content of large collections of text. However, traditional probabilistic topic modeling is limited to a small number of topics (typically no more than hundreds). We introduce fine-grained topic models, which have large numbers of nuanced and specific topics. We demonstrate that fine-grained topic models enable use cases not currently possible with current topic modeling techniques, including an automatic cross-referencing task in which short passages of text are linked to other topically related passages. We do so by leveraging anchor methods, a recent class of topic model based on non-negative matrix factorization in which each topic is anchored by a single word. We explore extensions of the anchor algorithm, including tandem anchors, which relaxes the restriction that anchors be formed of single words. By doing so, we are able to produce anchor-based topic models with thousands of fine-grained topics. We also develop metrics for evaluating token level topic assignments and use those metrics to improve the accuracy of fine-grained topic models.

Thesis advisor: Mary Ann Glynn / Categories are persistent features of cultural fields and markets, used to delineate boundaries between different kinds of cultural products and cultural producers. Categories are dynamic social constructions, evolving over time as their constitutive practices and meanings change, through a variety of processes that scholars are still describing and unpacking. This dissertation explores, in three papers, the processes through which categories change over time in the context of the field of jazz music, describing mechanisms of category change and theorizing processes of category evolution and decline. The first paper (chapter two) examines the emergence of a novel subcategory of jazz, called bebop, in the mid-1940’s, and the changes to jazz consumption practices and category meanings that bebop’s emergence wrought. It contributes to the categorization literature by highlighting the role of consumption practices in shaping category meanings. The second paper (chapter three) examines the emergence of another subcategory, called jazz fusion, in the 1960’s and 1970’s, and unpacks gatekeeper responses to its emergence in the form of critical discourse, revealing how category gatekeepers codify category change by reordering their standards of value, quality, and category membership through their discourse. It contributes to the literature by showing how gatekeepers discursively modify categories as they make sense of new practices. The third paper (chapter 4) explores the processes through which subcategories are absorbed into broader umbrella categories, falling out of use even as their constitutive practices and meanings live on. This paper contributes to the literature by expanding our understanding of category decline. Overall, this dissertation contributes to literature on category dynamics and the practice turn in organization theory. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Carroll School of Management. / Discipline: Management and Organization.

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Research has ranked electrochemistry as one of the more difficult topics to teach and learn. Examiners in South Africa have complained about the poor performance in electrochemistry related concepts in Grade 12 public exams. This may suggest that the physical science teachers may not be teaching it very well. Accomplished teachers use specialized knowledge to transform their knowledge of subject matter into a form that can easily be understood by learners, known as pedagogical content knowledge (PCK). Little is known about the quality of PCK of teachers within this topic and currently there is no instrument to measure quality of topic specific PCK of practicing physical science teachers. The main purpose of the study was to design and validate an instrument that could be used to measure the quality of topic specific PCK of practicing physical science teachers in electrochemistry. The study was a methodology study which used a Mixed Methods (MM) approach. MM were used because the design of the instrument requires both qualitative and quantitative methods in the various steps towards its creation. The topic specific PCK (TSPCK) theoretical framework guided the design of the instrument. TSPCK comprises of 5 components namely: (i) Learners’ Prior Knowledge including misconceptions; (ii) Curricular Saliency; (iii) What makes topic easy or difficult to understand; (iv) Representations or models; and (v) Conceptual teaching Strategies that enables transformation of content knowledge into its teachability. The new instrument was designed to elucidate TSPCK in electrochemistry according to these five components which each component represented a test item. The design process followed these steps chronologically: (i) Conceptualization of test items, (ii) construction of the instrument and judgment of items, (iii) piloting and construction of the actual instrument and finally validation of the instrument. After its conceptualization and development, the instrument was validated with a convenience sample of 21 practicing physical science teachers in Johannesburg schools, Gauteng province, South Africa. A topic specific PCK rubric was used to score the teachers’ responses on a 4 point scale-from 1 “limited” to 4 “Exemplary” Topic Specific PCK. The Rasch Winsteps program analysed the teachers’ scores and ascertained the validity of the instrument through statistics of goodness of fit. In addition, the Rasch 2 model determined the hierarchy difficulty of topic specific PCK components as well as instrument reliability. Both the items and persons’ responses fell within an acceptable conventional range of -2 and +2 Infit/outfit statistics. The item and person reliability indices of the developed instrument were 0.97 and 0.89 respectively. The results show that it is possible to design an instrument that is valid and reliable instrument. Data on content knowledge of teachers was collected using the Content Knowledge test. It was found that a high concentration of teachers possessed a sound knowledge of electrochemistry but with a corresponding low topic specific PCK. This is likely the reason of poor performance of grade 12 learners in exams on electrochemistry related topics. Furthermore, a positive statistically significant linear relationship was found to exist between Content knowledge and the measured teachers’ topic specific PCK. The findings suggest that TSPCK instrument might be used for teaching purposes so as to boost the practicing teachers’ TSPCK on electrochemistry. In addition, the findings suggest that the instrument might be incorporated as a training tool in inservice teacher workshops.

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Stack Overflow is a rich source of questions and answers—discussions—about software development. One topic of discussion is software design, such as the correct use of design patterns or best practices in data access. Since design is a more abstract topic in software engineering, researchers have long sought to characterize and model design knowledge. However, these approaches typically require significant expert input to contextualize the abstract design information. In this study, we explore how combining expert input with Stack Overflow might serve as an effective way to identify design topics. Being able to identify and classify this design knowledge would enable the discovery and sharing of this knowledge, enabling developers better leverage Stack Overflow for crowd-sourcing their design decisions. We first perform inductive coding of design-tagged Stack Overflow questions and answers to identify the design concepts that developers discuss. We report on areas where inter-rater agreement was a challenge, including abstraction levels. Since inductive coding is expensive, we apply a semi-supervised (Anchored CorEx) approach. We find that it outperforms LDA and offers superior interpretability and the ability to incorporate expert domain knowledge. We leverage Anchored CorEx to identify how design is discussed on Stack Overflow and leveraged in GitHub projects. We conclude by describing how our experience using the semi-supervised CorEx approach leads us to believe that approaches like Anchored CorEx that combine domain knowledge and scalability are key for analyzing large SE text repositories. / Graduate

Evaluation of student understanding of learning material is critical to effective teaching. Current computer-aided evaluation tools exist, such as Computer Adaptive Testing (CAT); however, they require expert knowledge to implement and update. We propose a novel task, to create an evaluation tool that can predict student performance (knowledge) based on general performance on test questions without expert curation of the questions or expert understanding of the evaluation tool. We implement two methods for creating such a tool, find both methods lacking, and urge further investigation.

The growing global population and climate change threaten the availability of many critical resources, and have been directly impacting the food and agriculture sector. Therefore, new cultivation technologies must be rapidly developed and implemented to secure the world's future food needs. Closed-loop greenhouse agriculture systems provide an opportunity to decrease resource reliance and increase crop yield. Greenhouses provide versatility in what can be grown and the resources required to function. Greenhouses can become highly efficient and resilient through the application of a closed-loop systems approach that prioritizes repurposing, reusing, and recirculating resources. Here, we employ a text mining approach to research the available research (meta-research) and publications within the area of closed-loop systems in greenhouses. This meta-research provides a clearer definition of the term “closed-loop system” within the context of greenhouses, as the term was previously vaguely defined. Using this meta-research approach, we identify six major existing research topic areas in closed-loop agriculture systems, which include: models and controls; food waste; nutrient systems; growing media; heating; and energy. Furthermore, we identify four areas that require further urgent work, which include the establishment of better connection between academic research to industry applications; clearer criteria surrounding growing media selection; critical operational requirements of a closed-loop system; and the functionality and synergy between the many modules that comprise a closed-loop greenhouse systems. / Thesis / Master of Applied Science (MASc)

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