A quality warning is useful only when people can understand it
An environmental dashboard marks an estimated temperature with a small coloured icon. Some users cannot distinguish the colour, while others do not know what it means. Accessibility requires quality information to be understandable across users and devices.
Use clear language
Explain observed, stale, estimated and unavailable states in terms relevant to the user’s decision.
Do not rely on colour alone
Text labels, symbols and suitable contrast can support users with different visual needs.
Preserve machine-readable meaning
API clients need consistent status fields as well as human-readable explanations.
Consider assistive technology
Interfaces should support appropriate keyboard and screen-reader access.
Avoid hiding uncertainty
A smooth graph should not conceal estimated or missing periods.
Test with representative users
Accessibility testing can reveal confusion that technical validation misses.
Break-test: a screen reader announces only the temperature
Can the interface also communicate that the value is stale or estimated?
Connected knowledge
See Quality Flag Consumer Testing, Quality Flag Governance and W3C Accessibility.