Usability and Accessibility
What does Accessibility mean to YOU?
Who needs accessibility?
- people who are born with disabilities
- people who acquire permanent disabilities
- people beyond the 95th percentile away from the mainstream
- people who currently have a temporary disability
- people who are disabled by their environment or other external
circumstances
- the elderly (since they are likely to be progressively getting
more and more disabled)
- children (since they are not yet enabled)
- pregnant women (who are not disabled - but may be experiencing
temporary limitations)
- people who are just plain slow or lazy
- people who are identified by law as being entitled to
accessibility
- people with a "handicaped parking skicker"
- people who don't want to use Internet Explorer
- people willing to self identify that they have a disability
Definitions from ISO 9241-11Guidance on usability
usability:
Extent to which a product can be used by specified users to achieve
specified goals with effectiveness, efficiency and satisfaction in a
specified context of use.
effectiveness:
Accuracy and completeness with which users achieve specified goals.
efficiency:
Resources expended in relation to the accuracy and completeness with
which users achieve goals.
satisfaction:
Freedom from discomfort, and positive attitudes towards the use of the
product.
context of use:
Users, tasks, equipment (hardware, software and materials), and the
physical and social environments in which a product is used.
Defintion from ISO TS 16071 Guidance on accessibility
accessibility
usability of a product, service, environment or facility by people with
the widest range of capabilities
NOTE Although “accessibility” typically addresses users who have a
disability, the concept is not limited to disability issues.
New Definition from ISO 9241-171 Guidance on software
accessibility
accessibility
usability of a product, service, environment or facility by people with
the widest range of capabilities
NOTE 1 The concept of accessibility addresses the full range of user
capabilities and is not limited to users who are formally recognised as
having a disability.
NOTE 2 The usability-orientated concept of accessibility aims to
achieve levels of effectiveness, efficiency and satisfaction that are
as high as possible consider
Newest Definition from ISO TC159 Ergonomics (Nov '07)
accessibility
extent to which products, systems, services, environments or facilities
can be used by people from a population with the widest range of
capabilities to achieve specified goals in a specified context of use
NOTE Context of use includes direct use or use supported by assistive
technology.
NOTE The definition of accessibility in ISO/FDIS 9241-171 and ISO/FDIS
9241-20 is a context specific definition for the field of interactive
systems. It shall be marked in the relevant standards with the subject
field 〈Interactive systems〉.
Date of last revision: Jan 7, 2008