A Dashboard Review Checks the Numbers Without the Picture

What We Keep Finding

Ask your dashboard a question with your eyes closed. Which region missed target last quarter? If the answer lives in a color-coded chart drawn on a canvas element, a blind analyst gets nothing. Not a wrong answer. Nothing. A canvas exposes no content to assistive technology at all. So the failure is not a contrast problem or a labelling problem, it is an absence, and it gets fixed at a different rule from the one people reach for.

Data tables have a quieter version of the same failure. A screen reader lands on a cell and reads "43", and without real header markup the user cannot tell whether that is revenue, headcount, or a date. The relationships between the numbers are the whole product, and they are exactly what visual design shows and markup forgets. Most table advice overcorrects here, so it is worth saying that a caption is not required, and neither is a scope attribute on every header. Headers that span groups of columns or rows want a scope value that says so. The heavyweight approach of wiring each cell to its headers by id is reserved for two narrow cases. One of them is a cross-tab with three or more headers per cell, which on a dashboard is the one place you may genuinely need it.

The good news about charts is how much cheaper conforming is than the rebuild everyone braces for. A chart carrying visible labels and values, or sitting above a data table with the same numbers in it, satisfies the graphical-contrast requirement outright rather than by scraping past it. There is one catch worth planning for, which is that adding those labels turns them into text, and text has to clear a higher contrast bar than a graphic does. And a heat map's gradient is excepted anyway, since the gradient is the measurement.

Two more that save you arguments. Color is one thing that cannot carry meaning alone, and position is a separate one. So a legend distinguished only by the order of its entries fails a different rule from a chart distinguished only by hue. A live KPI tile that updates on its own has to announce, and the usual implementation announces "43" instead of "revenue, 43". A live region reads only what changed unless somebody tells it to read the whole thing. And a greyed-out filter is excepted from the contrast rules, so we will not raise it and you should not let anyone else.