standards_quality

1. ISO/IEC 9126-1
Murad Huseynli

2. ISO/IEC
• ISO (the International Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized
system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International
Standards through technical committees established by the respective organization to deal with particular fields of technical activity.
• The fundamental objective of the ISO/IEC 9126 standard is to address some of the well-known human biases that can adversely affect the
delivery and perception of a software development project. These biases include changing priorities after the start of a project or not having
any clear definitions of "success". By clarifying, then agreeing on the project priorities and subsequently converting abstract priorities
(compliance) to measurable values (output data can be validated against schema X with zero intervention), ISO/IEC 9126 tries to develop a
common understanding of the project's objectives and goals.
• ISO/IEC 9126 consists of the following parts, under the general title Software engineering — Product quality:
Part 1: Quality model
Part 2: External metrics
Part 3: Internal metrics
Part 4: Quality in use metrics

3. Parts of Standard
• Quality Model
It describes quality model framework which explains relationships between different approaches to quality as well as identifying quality characteristics and sub-
characteristics of software products.
• External metrics
Its use is to describes external metrices that are used to measure characteristics and sub-characteristics which are identifies in part 1.
External metrics are applicable to running software.
• Internal metrics
Its use is to describes internal metrices that are used to measure characteristics and sub-characteristics which are identifies in part 1.
Internal metrics are those which do not rely on software execution (static measure).
• Quality in use metrics
Its use is to identify metrices which are used to measure effects of combined quality characteristics for user.
It is concluded that first three parts are concerned with describing and measuring quality of software product and fourth part concerned about quality of software product
from user point of view.

4. Categories of Quality Model
The standard provides a framework for organizations to define a quality model for a software product. On doing so, however, it leaves up to each organization the task
of specifying precisely its own model. This may be done, for example, by specifying target values for quality metrics which evaluates the degree of presence of quality
attributes.
The quality model presented in the first part of the standard, ISO/IEC 9126-1, classifies software quality in a structured set of characteristics and sub-characteristics :

5. Categories in detail
Each quality sub-characteristic (e.g. adaptability) is further divided into attributes. An attribute is an entity which can be verified or
measured in the software product. Attributes are not defined in the standard, as they vary between different software products.

6. Quality-in-use metrics
• Quality-in-use metrics are only available when the final product is used in real conditions. Ideally, the internal quality
determines the external quality and external quality determines quality in use.
• This standard stems from the GE model for describing software quality, presented in 1977 by McCall et al., which is
organized around three types of quality characteristic:
• Factors (to specify): They describe the external view of the software, as viewed by the users.
• Criteria (to build): They describe the internal view of the software, as seen by the developer.
• Metrics (to control): They are defined and used to provide a scale and method for measurement.
• ISO/IEC 9126 distinguishes between a defect and a nonconformity, a defect being "The nonfulfilment of intended usage
requirements", whereas a nonconformity is "The nonfulfilment of specified requirements". A similar distinction is made
between validation and verification, known as V&V in the testing trade.

7. ISO/IEC 25010:2011
• On March 1, 2011, ISO/IEC 9126 was replaced by ISO/IEC 25010:2011 Systems and software engineering - Systems and software Quality
Requirements and Evaluation (SQuaRE) - System and software quality models. Compared to 9126, "security" and "compatibility" were
added as main characteristics.
• ISO 25010 has eight product quality characteristics (in contrast to ISO 9126's six), and 31 subcharacteristics.
• "Functionality" is renamed "functional suitability". "Functional completeness" is added as a subcharacteristic, and "interoperability" and "security" are moved elsewhere. "Accuracy" is renamed
"functional correctness", and "suitability" is renamed "functional appropriateness".
• "Efficiency" is renamed "performance efficiency". "Capacity" is added as a subcharactersitic.
• "Compatibility" is a new characteristic, with "co-existence" moved from "portability" and "interoperability" moved from "functionality".
• "Usability" has new subcharacteristics of "user error protection" and "accessibility" (use by people with a wide range of characteristics). "Understandability" is renamed "appropriateness
recognizability", and "attractiveness" is renamed "user interface aesthetics".
• "Reliability" has a new subcharacteristic of "availability" (when required for use).
• "Security" is a new characteristic with subcharacteristics of "confidentiality" (data accessible only by those authorized), "integrity" (protection from unauthorized modification), "non-repudiation" (actions
can be proven to have taken place), "accountability" (actions can be traced to who did them), and "authenticity" (identity can be proved to be the one claimed).
• "Maintainability" has new subcharacteristics of "modularity" (changes in one component have a minimal impact on others) and "reusability"; "changeability" and "stability" are rolled up into
"modifiability".
• "Portability" has "co-existence" moved elsewhere.

8. Product Quality Model -ISO/IEC 25010:2011

9. Quality in use model-ISO/IEC 25010:2011
• Quality in use is the degree to which a product or system can be used by specific users to meet their needs to achieve specific goals with effectiveness, efficiency,
freedom from risk and satisfaction in specific contexts of use.
• The properties of quality in use are categorized into five characteristics: effectiveness, efficiency, satisfaction, freedom from risk and context coverage

10. Thank You