A Grammar for Hypothesis-Driven Visual Analysis

A hallmark of visual analytics is its ability to support users in translating broad, open-ended analytic questions (e.g., "is our company succeeding?") into verifiable hypotheses that can be tested from the available data (e.g., "our total revenue increased this past quarter"). However, the process of converting open-ended analytic questions into testable hypotheses is complex and often ill-defined. Beyond high-level descriptions, the visual analytics literature lacks a formalization that can be operationalized for analysis and automation. In this paper, we propose a novel grammar to express hypothesis-based analytic questions for visual analysis. Drawing from prior work in science and education, our grammar defines a formal way to express sets of verifiable hypotheses as a "hypothesis space". Our proposed use of hypothesis spaces contributes a new lens to unify concepts of user goals, the capabilities of a dataset, visual analysis, and testable hypotheses. As a result, we can reformulate abstract classes of visual analysis goals, such as analytic and data-related tasks, in a way that is suitable for analysis and automation. We demonstrate use cases of our grammar in real-world analytic applications including VAST challenges, Kaggle competitions, and pre-existing task taxonomies. Finally, we provide design opportunities in which our grammar can be operationalized to articulate analysis tasks, evaluate visualization systems, and support hypothesis-based reasoning in visual analytic tools.