Which of the following elements does NOT affect the accessibility of a dashboard?

The accessibility of a dashboard is primarily concerned with its usability and the extent to which users can effectively interact with and interpret the data presented. Access permissions are crucial because they determine who can view or manipulate the dashboard. User roles also directly influence accessibility since different roles may have varying levels of access or different data relevant to their position. Data optimization affects how quickly and effectively data can be retrieved and displayed, affecting user interaction with the dashboard.

Color schemes, while they can impact usability in terms of visual comfort or clarity, do not fundamentally change whether a user can access or interact with a dashboard's data. Accessibility focuses more on structural elements such as roles, permissions, and data organization rather than aesthetic choices like color. Therefore, color schemes are the element that does not significantly affect the overall accessibility of a dashboard.