Complex information can benefit from supplementary visual representations. Oftentimes, it’s a legal requirement to include information in various forms to maintain accessibility.
Simple graphics should have a brief and informative text alternative, for example, your alt text may read: "population graph" for a simple graph analyzing a population. Complex graphs need detailed alternative text to convey the information the graphic is displaying. This can include categories of data, trends, and the greatest or smallest values.
In this example, we're going to provide a text alternative for a graph. We'll use HTML to give an alt attribute to the graph as well as some paragraph text.
The following graph has too much information to describe in alternative text. Instead, we’ll describe it in the introduction. By placing a paragraph first, we also make sure screen reader users can get all the information.
Comparing the frequency of U.S. student disabilities in 2016 versus 2019
As the population increases so will the prevalence of disabilities. A 2019 study confirms this after surveying various disabilities amongst U.S. students in 2016 and 2019. Disabilities included: Attention Deficit Hyperactivity Disorder (ADHD), chronic health problems, learning, psychological, mobility, visual, and hearing disabilities. Also included was a broad "other" category. One of their biggest findings was that ADHD had doubled, and psychological disabilities had tripled. Mobility, visual, deaf or hard of hearing, and other disabilities had remained stable.
The alternative text for the above graph might look like this:
alt=“Bar chart comparing the number of U.S. students from 64 schools that reported having a type of disability in 2016 and 2019”