Collaborative Environments: Accessibility and Usability for Users with Special Needs - Community-Built Databases: Research and Development - page 336

proposes metrics to measure either the time taken to load a Web page or the time
span between the moment that a user clicks on a selection and the moment that a
new element appears on the screen. For metrics related to each criterion see [ 23 ].
The accessibility factor . It is used to understand the capability of an interactive
environment to be used by people with special needs. The QUIMmodel, and the one
we present here, considers the accessibility factor as a possible facet of the usability
problem and proposes a set of criteria to address accessibility issues for different
types of disability. We remark that in the literature there are other interpretations of
the relationship existing between usability and accessibility. These two aspects have
been presented as nonintersecting or intersecting, or one as a subproblem of the other
(see, for example, [ 24 ] for a discussion on their mutual relationship). However, our
position is that accessibility is one of the facets of usability.
To evaluate user interface problems specifically related to accessibility, the QUIM
model proposes criteria that address issues faced by users affected by the forms of
disability discussed in Sect. 13.2 . We consider accessibility to be of great importance
in the context of collaborative e-learning systems. Our proposal adopts the QUIM
accessibility factor in order to provide measures of performance and satisfaction
for all possible users according to the international regulations defined by WAI.
Table 13.6 extends the information on the accessibility factor of Table 13.5 ,also
associating WCAG 2.0 with the QUIM criteria and providing an idea of the strict
interlacing existing between the two models. A letter A in the third column indicates
that a QUIM factor has a counterpart in the WCAG 2.0 accessibility guidelines,
possibly expressed with a slightly different terminology (criteria that influence
neither usability nor accessibility are omitted). This confirms our assumption that
accessibility should be considered as a facet of the usability problem.
The universality and acceptability factors . The universality factor includes the
interactive environment support for the activities of users with different profiles,
cultures, contexts of use, and technology used to access it; whereas the acceptability
factor can be used to quantify the extent to which an environment is comfortable.
The criteria related to these factors are reported in Table 13.5 and detailed in [ 23 ].

Table 13.6 The relations
among QUIM accessibility
and WCAG 2.0

QUIM WCAG 2.0

Consistency X A

Controllability X A

Flexibility X A

Minimal action X

Minimal memory load X A

Navigability X A

Operability X A

Readability X A

Self-descriptiveness X

Simplicity X

Time behavior A

Understandably A

User guidance X A