An Investigation of the Weaknesses of the ISO 9126 International ...

these characteristics were presented using the
structured hierarchy of ISO 9126 [16].
4) Bøegh [17] stated that he could not apply the ISO
9126 metrics directly because they are imprecise. In
addition, the project team in his study devoted
considerable effort to redefining the metrics and
applying the formalized approach with counting rules
and profiles [17]. The complex attributes based on
standards required a careful examination of the
standards, but they eventually turned out to be easier
to define [17].
5) Koscianski and Costa [18] stated that the
normalization of metrics and scores must accomplish
the following: every metric used must be mapped to
the same reference scale [18]. The sample metrics of
ISO/IEC 9126-2 and ISO/IEC 9126-3 generally
return values in the range [0, 1], where 1 means the
best possible result. Furthermore, qualitative metrics
may use the same concept [18].
6) Behkamal et al. [19] stated that the ISO 9126 quality
model is a general one. In addition, they noted that in
order to apply this standard, it needs to be
customized [19].
7) Erazo [20] has analyzed the ISO 9126 quality model
and presented the results of an actual evaluation,
illustrating each characteristic with their respective
valued aspects.
V. CONCLUSION
Nowadays, ISO is ongoing to update the current ISO
9126 international standard on software product quality
measurement. However, this current standard will be
replaced by the upcoming quality measurement division
(ISO 25020, ISO 25021, ISO 25022, ISO 25023, and ISO
25024) of the ISO 25000 series of international standards on
software quality requirements and evaluation (SQuaRE).
This paper presented an investigation on the weaknesses
of the current ISO 9126 international standard by collecting
different viewpoints from our previous researches and from
interested researchers and practitioners. However, this paper
has tackled the following suggestion to resolve such
weaknesses:
• Ensure that the terminology on software product
quality measurement is fully aligned with the classic
measurement terminology in the sciences and in
engineering.
• Identify and classify the ISO 9126 metrics into base
and derived metrics to make it easy to determine
which base metrics should be collected to be used
subsequently in computing the other derived metrics.
• Convert the result of the ISO 9126 metrics to
percentage values to be more understandable.
• To overcome the problem on the mapping between
ISO 9126 and ISO 12207, a cross-reference numbers
from ISO 12207 can be used. For example, the
cross-reference number 5.3.9 is referring to “primary
processes”, ‘development process’ and ‘software
qualification testing’ activity, respectively, Fig. 3 for
an example on where the ISO 9126 internal quality
metrics could be measured within the ISO 12207
verification activities.
• Ignore the compliance sub-characteristic for each
characteristic in ISO 9126 quality model.
• Additional empirical work is necessary for clarity
and validates the ISO 9126 quality model structure
in terms of characteristics and sub-characteristics.
• The usability characteristic should be extended to
include more specific sub-characteristics such as
consistency, simplicity, legibility, color use, and
help.
• Include the addition of two characteristics to the ISO
9241-11 standard which had been selected as their
baseline: learnability and security. Then, specific
metrics for these characteristics need to be presented
using the structured hierarchy of ISO 9126.
• Redefine the ISO 9126 metrics and apply a
formalized approach with counting rules and profiles
to the ISO 9126 metrics.
• Map each of the ISO 9126 metrics to the same
reference scale.
• Make the ISO 9126 be ready for customization to be
used in any domain.
• The ISO 9126 quality model characteristics need to
be ranked by their usability and importance.
REFERENCES
[1] ISO, Software Product Evaluation - Quality Characteristics
and Guidelines for Their Use (ISO/IEC IS 9126). Geneva,
Switzerland: International Organization for Standardization
1991.
[2] ISO, Software Engineering - Product Quality - Part 1: Quality
Model (ISO/IEC IS 9126-1). Geneva, Switzerland:
International Organization for Standardization, 2001.
[3] ISO, Software Engineering - Product Quality - Part 2:
External Metrics (ISO/IEC TR 9126-2). Geneva, Switzerland:
International Organization for Standardization, 2003.
[4] ISO, Software Engineering - Product Quality - Part 3: Internal
Metrics (ISO/IEC TR 9126-3). Geneva, Switzerland:
International Organization for Standardization, 2003.
[5] ISO, Software Engineering - Product Quality - Part 4: Quality
in-Use Metrics (ISO/IEC TR 9126-4). Geneva, Switzerland:
International Organization for Standardization, 2004.
[6] M. Azuma, "SQuaRE: The Next Generation of ISO/IEC 9126
and 14598 International Standards Series on Software Product
Quality," Proc. of the European Software Control and Metrics
Conference (ESCOM’01), London, UK, 2001, pp. 337-346.
[7] ISO, Software Engineering - Software Product Quality
Requirements and Evaluation (SQuaRE) - Guide to SQuaRE
(ISO/IEC 25000), Geneva, Switzerland: International
Organization for Standardization, 2005.
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