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analyzing usage data from real end-users, while inspection methods are performed by
expert evaluators or designers and are based on reviewing the usability aspects of
Web artifacts, which are commonly user interfaces, with regard to their conformance
with a set of guidelines.
Usability inspection methods have emerged as an alternative to empirical methods
as a means to identify usability problems since they do not require end-user participa-
tion and they can be employed during the early stages of the Web development proc-
ess [9]. There are several proposals based on inspection methods to deal with Web
usability issues, such as the Cognitive Walkthrough for the Web (CWW) [4] and the
Web Design Perspectives (WDP) [10]. CWW assesses the ease with which a user can
explore a Website by using semantic algorithms. However, this method only supports
ease of navigation. WDP extends and adapts the heuristics proposed by Nielsen [21]
with the aim of drawing closer to the dimensions that characterize a Web application:
content, structure, navigation and presentation. However, this kind of methods tends
to present a considerable degree of subjectivity in usability evaluations.
Other works present Web usability inspection methods that are based on applying
metrics in order to minimize the subjectivity of the evaluation, such as the WebTango
methodology [14] and Web Quality Evaluation Method (WebQEM) [22]. The Web-
Tango methodology allows us to obtain quantitative measures, which are based on
empirically validated metrics for user interfaces, to build predictive models in order to
evaluate other user interfaces. WebQEM performs a quantitative evaluation of the
usability aspects proposed in the ISO 9126-1 standard [15], and these quantitative
measures are aggregated in order to provide usability indicators.
The aforementioned inspection methods are oriented towards application in the
traditional Web development context; they are therefore principally employed in the
later stages of Web development processes. As mentioned above, model-driven Web
development offers a suitable context for early usability evaluations since it allows
models, which are applied in all the stages, to be evaluated. This research line has
emerged recently, and only a few works address Web usability issues, such as those
of Atterer [3], Abrahão and Insfran [2], and Molina and Toval [19].
Atterer [3] proposed a prototype of a model-based usability validator with which to
analyze models that represent enriched Web user interfaces. This approach takes
advantage of models that represent the navigation (how the Website is traversed), and
the UI of a Web application (abstract properties of the page layout).
Abrahão and Insfran [2] proposed a usability model to evaluate software products
that are obtained as a result of model-driven development processes. Although this
model is based on the usability sub-characteristics proposed in the ISO 9126 standard
[15], it is not specific to Web applications and does not provide specific metrics. The
same model was used in [24] with the aim of providing metrics for a set of attributes
which would be applicable to the conceptual models that are obtained as a result of a
specific MDWD process.
Molina and Toval [19] presented an approach to extend the expressivity of models
that represent the navigation of Web applications in order to incorporate usability
requirements. It improves the application of metrics and indicators to these models.
Nevertheless, to the best of our knowledge, there is no generic process for integrat-
ing usability evaluations into Model-Driven Web development processes.
