Data visualization is the translation of data in the form of words and numbers to a visual format, using color, size, shape, and placement to convey trends and patterns in the data which can be much less apparent when looking at tables of numbers or words. Thus data viz communicates best to those with full visual capabilities. To make charts, graphs, and maps accessible to those with visual impairment, we must translate the meaning of a visualization back into words, which can be a challenge. Amy Cesal's article, Writing Alt Text for Data Visualization, can help us address that challenge.
Alt text is a brief description meant to provide the meaning and context of a visual item in a digital setting. And although Cesal notes that, in most cases, it’s impossible to write something short that conveys the whole meaning of a visualization, she maintains that an incomplete description is better than none at all. Here are Cesal’s simple guidelines for alt text for data viz:
Chart type: It’s helpful for people with partial sight to know the chart type. This information provides context for understanding the rest of the visual. Example: Line graph.
Type of data: What data is included in the chart? The x and y axis labels may help you figure this out. Example: number of clients served per day in the last year.
Reason for including the chart: Think about why you’re including this visual. What does it show that’s meaningful? There should be a point to every visual and you should tell people what to look for. Example: more clients are served during the winter months.
Cesal also suggests that you include a link to the raw data somewhere in the surrounding text.
For a deeper dive into this topic, checkout Image Description Guidelines from the Diagram Center.
To see past data tips, click HERE.
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Got the feeling that you and your colleagues would use your data more effectively if you could see it better? Data Viz for Nonprofits (DVN) can help you get the ball rolling with an interactive data dashboard and beautiful charts, maps, and graphs for your next presentation, report, proposal, or webpage. Through a short-term consultation, we can help you to clarify the questions you want to answer and goals you want to track. DVN then visualizes your data to address those questions and track those goals.
