Information Technology Reference
In-Depth Information
4.3 Collection of the Data
The data for this case study was collected during the
execution of the evaluation
stage
of WUEP. As an example, we show values obtained after the evaluators applied cer-
tain operationalized metrics to the excerpts of models that are shown in Figure 2.
In the NAD (Fig. 2 (a)), the value of the Compactness metric is: Cp (NAD) = (448-
347) / (448-56) = 0.26 since the components of the formula are: n=k=8; Max=448;
Min=56; and ∑i ∑j Dij=347. The rating level of this metric (0.2 < x ≤ 0.8) therefore
indicates that there is no usability problem related to the Interconnectivity attribute in
this NAD.
In the APD (Fig. 2 (b)), the value of the Discernible links metric is: DL (APD) = 1-
0.5(2/5+3/13) = 0.68 since there are 2 links (
title_and_author
and
report_title
) that
might be confused with labels, and there are 3 labels (
date
,
content
and
BD_content
)
that might be confused with links as a result of their visual properties. The rating level
of this metric (0.5 < x ≤ 0.7) therefore indicates the existence of a medium usability
problem (UP001) related to the Clickability attribute in this APD.
Each evaluator presented the usability problems detected in usability reports by us-
ing the defined template. As an example, Table 1 shows an excerpt of the usability
report that is presented in the UP001.
Table 1.
Usability problem detected: UP001
ID
UP001
title_and_author
and
report_title
links are confused with labels, whereas
date
,
content
and
BD_content
labels are confused with links.
Description
Affected attribute
Appropriateness recognisability / Navigability / Clickability
Severity level
Medium (0.68)
Artifact evaluated
Abstract Presentation Diagram (APD no. 3)
Source problem
Abstract Presentation Diagram (APD no. 3)
Occurrences
5 errors in the same APD
Change the visual properties of links and labels to another face/color in order for
them to be discernible. The use of typographies, such as blue, and an underlined
face for links is recommended.
Recommendations
4.4 Analysis of Data
The usability problems reported in the execution stage were analyzed to address our
research questions.
Usability Problems and their Implications for Intermediate Artifacts.
The evalua-
tion performed for the case study only considers two different abstraction levels: the
platform-independent models: class model, navigational model (NADs), and presenta-
tion model (APDs); and the code model: final user interfaces.
With regard to the class model, a mean of 0.6 UPs (std. dev. 0.54) were detected by
the evaluators since the expressiveness of its modeling primitives makes it difficult to
operationalize metrics. However, UPs related to the minimization of user effort were
detected (e.g.,
“does not provide default values for elements that are needed for user
input”
). These can be solved by correcting the class model itself by adding default
values to attributes from classes.
