Haley Jeppson (NISS Research Associate) joined NISS in October of 2021 and has been working with NCES (National Center for Education Statistics) on the Innovative Graphics for NCES Online Reports research project. The project’s objective is the enhancement of graphical data displays in reports and briefs, ensuring the graphs are engaging, accessible, efficient, and statistically accurate, fostering effective data communication, and encouraging viewer engagement and navigation. This project has coalesced into a comprehensive data visualization handbook containing guidelines for best practices, tutorials, and a reference library.
Government reports face the challenge of requiring engaging and useful visualizations for diverse audiences that adhere to the agency standards. This process typically includes navigating agency style guides and recommendations, the latest statistical and visualization best practices, accessibility standards, and legal requirements, though challenges arise when simultaneously meeting these requirements. Topics of particular interest include: (1) Guidance on selecting aspect ratios to ensure important patterns and trends in statistics are clearly described and easy to see; (2) Including uncertainty; (3) Developing a flexible yet concise set of color scales suitable for various data types; and (4) Navigating 508 compliance and accessibility.
Data Visualization Best Practices
Visual content can influence how people use data and make decisions. Thus, it is crucial to provide careful and objective content and recognize when visualizations may have underlying bias, error, or even implicit bias that data creators may not be aware of. The most important visualization priority for data analysts is preserving the integrity of data without introducing features that distort or distract from their meaning.
Many years of empirical evaluation of the perception and utility of statistical graphics has culminated in a working knowledge of how to best create graphs that are easily read and understood. Much historical research is centered around cognitive principles such as preattentive features, the Gestalt principles of visual perception, and Cleveland’s hierarchy of comparisons; design considerations such as the theming, background components, typography, and aspect ratio; the use of color, which includes the types of color palettes for various data, perceptual uniformity, and color blindness; and accessibility which includes compliance with WCAG (Web Content Accessibility Guidelines) and Section 508 of the Rehabilitation Act of 1973.
Active research areas include best practices for visualizing uncertainty and the complications that arise when complying with web standards and Section 508. For example, there are notable flaws in the WCAG color contrast requirements and work on a suitable solution is ongoing.
Consistent adoption of best practices enhances the translation of academic research into practice, though it is also important to consider the different purposes that motivate a data visualization and the intended audience and reach of the chart, which will influence its form and complexity. This research can guide the data visualization decisions by suggesting the more appropriate graph type, variable mappings, and use of color. For instance, considering the gestalt principles of visual perception helps take advantage of the human visual system’s ability to process large amounts of visual information with relatively little effort. Understanding the principles that underlie this processing allows us to create charts that require less cognitive effort to read, freeing us to think about the content rather than the form of the chart.
This research is distilled into the NCES data visualization handbook with guidelines for enhancing data visualizations, ensuring they highlight the comparison of interest, convey the information effectively, apply color appropriately, and maintain 508 compliance. These guidelines support effective data analysis and communication throughout the education agency.
To learn more about Haley’s work you might consider joining the JSM Rountable Session (#212 - Government Statistics Section A.M. Roundtable Discussion on Tuesday, August 9, 2022 : 7:00 AM to 8:15 AM) that she, Brian Habing and Heike Hoffman will be hosting entitled, “Combining Visualization Best Practices with Agency Standards for Statistical Graphics in Government Reports”.