Comparison of Software Quality Models - An Analytical Approach

International Journal of Emerging Technology and Advanced Engineering

Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 2, February 2012)

111

Comparison of Software Quality Models: An Analytical

Approach Sanjay Kumar Dubey

1, Soumi Ghosh

2, Prof. (Dr.) Ajay Rana

3

1Amity University, Sec-125, NOIDA, India



[email protected]

[email protected] [email protected]

Abstract— With the objective of presenting qualitative

software system most of the software producers have

endeavoured and infact this is their main purpose. Software

quality is having multi-dimensional content which may be

distinguished and measured easily. To be specific, with the

idea of determining the multidimensional content in a more

exact pattern various qualitative models have been presented

by virtue of which different aspects of this matter have been

attempted to be investigated properly. Practically as because

there are existences of different models which have used

different expressions the comprehension of this basic content

have become to some extent hard or difficult. Attempts have

been made in this particular paper to introduce some models

that have been mentioned and more clearly analysis the

qualitative characteristics and side-by-side determine the

software quality along with the analytical comparison of these

models. This paper may serve the purpose of a reference for

investigating software quality and its related models.

Keywords—Quality, Models, Analysis, System

I. INTRODUCTION

Software quality plays an important role in success of

the overall software system. So it is considered as a very

important aspect for the developers, users and project

managers. Software quality is the extent to which an

industry-defined set of desirable features are incorporated

into a product so as to enhance its lifetime performance

[11]. For any software system there must be following

three specifications such as functional specification (what

system is to do), quality specification (how well the

functions are to operate), resource specification (how much

is to be spent on the system). Quality comprises all

characteristics and significant features of a product or an

activity which relate to the satisfying of given requirements

(German Industry Standard DIN 55350 Part 11).

Quality is the total of features and characteristics of a

product or a service that bears on its ability to satisfy the

given needs (ANSI/ASQC A3/1978). Software quality has

been categorized into two parts by Deutsch et al. [8] as

software procedure quality and software product quality.

Software engineering related elements like technology,

tools, people, organisation and equipment were used in

software procedure quality. However, software product

quality consists of certain aspects like document clarity and

integrity, design trace-ability, program reliability and test

integrity as its basic characteristics. A quality model is

usually defined as a set of characteristics and relationships

between them which actually provide the basis for

specifying the requirements of quality and evaluating

quality [20]. It is also defined as a structured set of

properties that are needed for an object of a class to meet

defined purposes [12]. The benefit of quality model is

given by decomposition of valuable object like process,

product or organisation in the list of its characteristic/sub-

characteristics measures. It is applicable for predicting,

assuring and verifying the achievement of a defined goal.

Quality, apart from describing and measuring the

functional aspects of software also describes the extra

functional properties such as how system is built and how it

performs.

This paper describes various quality models and their

analytical comparison, determines software qualification

and its qualitative characteristics more clearly. Different

software quality models were proposed for software

applications by various researchers. The ISO/IEC 9126-

1[18] model which actually incorporates the findings of

various other models i.e. Mc Call[31], Boehm[4],

Dromey[9] etc. has been considered as the most prominent

model and this has been widely accepted and recognised as

a basic model in field of industry and research.



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II. LITERATURE SURVEY

The requirement to establish a quality model has been

felt by users for the purpose of evaluating the software

quality quantitatively and qualitatively. The quality models

which are present nowadays are most hierarchical models

based on quality criteria and associated metrics. All such

models are categorized into three kinds according to the

means by which these models have been generated. First

one is the theoretical model based on the hypothesis

relations among variables. Second one is the data-driven

which are based on statistical analysis. Third is the

combined model in which intuitions are used to determine

the basic type of the model and data analysis is used to

determine the constants of the model. Practically in most of

the cases the combined model is adapted. A. Mc Call Model:

The first quality model was proposed by Mc Call J. A.

[31]. The proposal of the model was basically meant to

design a complete layout the products quality through its

various characteristics. The quality of software has been

categorized in three different parts in this model namely

Product Revision (maintainability, flexibility and

testability, which contribute to product revision), Product

Operation (correctness, reliability, efficiency, integrity and

usability contribute to product operation) and Product

Transition (portability, reusability and interoperability

which contribute to product transition).

B. Boehm Model: Boehm’s [4] quality model presents the characteristics of

software on a larger scale as compare to Mc Call’s model.

In this model As-Is-Utility describes how easily, reliably

and efficiently software product can be used,

maintainability describes how easily modified and retest

the software product, and portability describes how the

software product can be used even when environment has

been changed.

C. FURPS Model: FURPS model [15] proposed by Grady B. R. and Hewlett

Packard Co. categorized characteristics into two different

requirements such as Functional Requirements (F) which is

defined by expected input & output and Non Functional

Requirements in which U stands for Usability (includes

human factors, aesthetic, documentation of user and

material of training), R stands for Reliability (includes

frequency and severity of failure, recovery to failure,

time among failure), P stands for Performance (includes

functional requirements) and S stands for Supportability

(includes backup, requisite of design, implementation,

interface and physiosts).

Figure i. Mc Call’s Software Quality Model

D. Ghezzi Model: Ghezzi C. et al. [14] state that internal qualities deal with

the structure of software which helps the software

developers to achieve those external qualities for which

software users care a lot and also provided both the internal

and external qualities of software which are Accuracy,

Flexibility, Integrity, Maintainability, Portability,

Reliability, Reusability and Usability.

Software

Quality

Correctness

Reliability

Efficiency

Integrity

Usability

Maintainability

Testability

Flexibility

Portability

Interoperability

Reusability

Traceability

Machine independence

Data Commonality

Communications

Commonality

Consistency

Completeness

Accuracy

Error Tolerance

Execution Efficiency

Instrumentation

Self descriptiveness

Expandability

Generality

Modularity

Software System

Independence

Conciseness

Simplicity

Communicativeness

Training

Operability

Access Audit

Access control



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Figure ii. Boehm’s Quality Model

E. IEEE Model: IEEE [17] is basically standard for software maintenance

to provide a qualitative model. In this standard an iterative

process for management and execution of software

maintenance activities has been described. Other standards

like software quality assurance, verification and validation,

software configuration management in which associated

processes (external processes) are defined. This model

shows various measurement ways of qualitative factors and

represents factors such as Efficiency, Functionality,

Maintainability, Portability, Reliability and Usability.

F. Dromey’s Quality Model: Dromey G. R. [9] quality model is based on evaluation

criteria. In other words, it aims at evaluating the quality of

the product when each software product has different

quality then the other.

Figure iii. FURPS Model

This model helps in predicting defects and indicates the

properties that were violated in order to create defects. This

model is designed on the relationship between quality

attributes and sub-attributes between software properties

and software quality attributes.

G. SATC’s Quality Model: Software Assurance Technology Center (SATC) Hyatt

L. E. et al. [16] which is engaged for NASA with the

objective of improving the software quality is actually

helping the software managers in establishing metrics

programs which may meet their basic needs with minimum

Functionality

Usability

Joint of characteristics

Capacities

Human Factors

Aesthetic

Documentation of the user

Material of training

Frequency and severity of failures

Recovery to failures

Time among failures

Velocity

Efficiency

Availability

Time of answers

Time of Recovery

Utilization of resources

Testability

Extensibility

Adaptability

Maintainability

Compatibility

Configurability

Installability

Serviceability

Localizability

Reliability

Performance

Supportability

Security

Software

Quality

Portability

As –Is-

Utility

Maintainability

Testability

Understandabili

ty

Modifiability

Structured-ness

Self

descriptiveness

Accountability

Accessibility

Communicativene

ss

Legibility

Conciseness

Structuredness

Self descriptiveness

Structurednes

Augmentability

Device

Independence

Self containedness

Reliability

Efficiency

Human

Engineering

Integrity

Accuracy

Accountability

Accessibility

Communicativeness



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Figure iv. Ghezzi Model

costs and it is also interpreting the resulting metrics in the

context of the supported projects. The SATC helps in

defining and testing a quality model for software by using

the results of these metric programs and discussions with

the projects as its basis. The SATC’s quality model defines

a set of goals related to the software product and process

attributes following the structure of the ISO 9126-1

software quality model.

H. ISO 9126-1 Quality Model: ISO 9126-1 [18] quality model has two main parts

consisting of Internal and External Quality Attributes and

Quality in Use Attributes. The Internal quality attributes

refers to the properties of the system that can be evaluated

without executing it while External quality attributes refers

to the system properties that may be evaluated by observing

the system during its execution. The quality in use

attributes refers to the properties of the system that are

experienced by the users of the system when the system is

in operable condition and also during its maintenance. The

characteristics of this model are Efficiency, Functionality,

Maintainability, Portability, Reliability and Usability.

I. QMOOD: Bansiya et al. [3] proposed a hierarchical Quality Model

for Object-Oriented Design (QMOOD) which extends

Dromey’s quality model methodology and involves four

levels as follows:

Figure v. IEEE Model

i. Identifying design quality characteristics:-The set of

design quality attributes that were used in QMOOD to

describe the characteristics of object-oriented systems

are functionality, effectiveness, understand-ability,

extendibility, reusability and flexibility.

ii. Identifying object-oriented design properties:-Design

properties can be determined by examining the internal

and external structure, functionality of design

components, attributes, methods and classes.

Qualities

Integrity

Reliability

Usability

Accuracy

Maintainability

Flexibility

Reusability

Portability

Efficiency

Temporal Efficiency

Resource Efficiency

Non deficiency

Error tolerance

Availability

Completeness

Accuracy

Security

Compatibility

Interoperability

Testability

Extensibility

Correctability

Hardware Independency

Software Independency

Installability

Reusability

Comprehensibility

Ease of Learning

Usability

Communicativeness

Reliability

Functionality

Supportability

Portability

Usability



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Figure vi. Dromey’s Quality Model

The structural and object-oriented set of design

properties that were used in QMOOD are design size,

hierarchies, abstraction, encapsulation, coupling,

cohesion, composition, inheritance, polymorphism

messaging, complexity.

iii. Identifying object-oriented design metrics:-The various

object-oriented design metrics are design size in classes

(DSC), Number of Hierarchies (NOH), Average

Number of Ancestors (ANA), Data Access Metric

(DAM), Direct Class Coupling (DCC), Cohesion

among Methods of class (CAM), Measure of

Aggregation (MOA), Measure of functional Abstraction

(MFA), Number of Polymorphic methods (NOP), Class

Interface Size (CIS), Number of Methods (NOM).

iv. Identifying object-oriented design properties:-The

design components were identified to determine the

architecture of object-oriented designs such as objects,

classes, generalization-specialization structures, class

hierarchies. This model identified the paradigm (e.g.

polymorphism, inheritance, data abstraction etc.) and

also introduces a set of new object-oriented metrics.

J. Other Quality Models: Kazman et al. [25] model presented two different

thoughts regarding the quality characteristics during the

software existence cycle. These qualitative characteristics

can be summarized as follows:

i) efficiency, security, availability and function;

ii) modifiability, portability, reusability, inheritability and

testability.

Figure vii. ISO 9126-1 Quality Model

A quality model Khosravi K. et al. [28] process consists

of two tasks i.e. i) choose a super-characteristic and ii)

choose and organize characteristics related to super

characteristic. This quality model is constructed based on

software reusability as super-characteristics and focus on

reusability, understandability, flexibility, modularity,

robustness, scalability, usability.

Functionality

Reliability

Usability

Efficiency

Portability

Maintainability

Accuracy

Testability

Changeability

Stability

Maintainability Compliance

Suitability

Interoperability

Security

Maturity

Fault Tolerance

Recoverability

Understand ability

Learnability

Operability

Time behavior

Resource Behavior

Analyzability

Adaptability

Install ability

Conformance

Replace ability

Implementation

Correctness

Internal

Contextual

Descriptive

Functionality, Reliability

Maintainability, Efficiency, Reliability

Maintainability, Reusability, Portability,

Reliability

Maintainability, Reusability, Portability,

Reliability



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This model organized quality characteristics and sub-

characteristics using the definitions from IEEE, ISO/IEC

and several other software quality models.

In order to evaluate software quality by means of

integrating the fuzzy theory and AHP (Analytic Hierarchy

Process) the guidelines were provided by Chang et al. [7]

and this quality assessment approach was applied on ISO

9126-1 quality model. The software quality evaluations

were based on the characteristics and sub-characteristics of

ISO 9126-1 model.

A component based software development quality model

was proposed by Sharma A. et al. [34] which include the

entire characteristics and sub-characteristics of ISO 9126-1

quality model. It also comprises of new proposed sub-

characteristics i.e. re-usability, flexibility, complexity, track

ability, scalability. Analytic Hierarchy Process (AHP) was

used in order to evaluate overall quality component.

Khomh F. et al. [27] proposed a method DEQUALITE

(Design Enhanced Quality Evaluation) to build a quality

model to measure the quality of object-oriented systems

with the help of their internal attributes and their designs

and measure system by analyzing the impact of design

patterns, antipatterns, and code smells on different software

quality characteristics.

An Aspect-Oriented Software Quality Model

(AOSQUAMO) was proposed by Kumar et al. [30] which

was an extension of ISO 9126-1 software quality model.

This model has also included four new sub-characteristics

i.e. modularity, code-reusability, complexity and reusability

in addition to original characteristics and sub-

characteristics of ISO 9126-1 quality model.

A UML conceptual model REASQ (Requirements,

Aspects and Software Quality) was developed by Castillo

I. et al. [6] to clarify the AOSD (Aspect-Oriented Software

Development) terminology i.e. aspect, composition,

(functional, non-functional, cross-cutting) concern,

(functional, non-functional) quality or (inherent, assigned)

property requirements for the software product. Comparing

REASQ model, ISO 9126-1 (2007) is used to relate the

requirement engineering terminology with the aspect-

orientation and software quality.

Sehra S. K. et al. [33] developed a model based on PSO

(Particle Swarm Optimization), a computational method

aimed at optimizing a problem through improvement of a

solution in regard to a given measure of quality. This

method is actually a refinement of the fuzzy estimates

meant for the development of software projects and it gives

nearly the same results like different basic models.

III. LAYERED APPROACH OF QUALITY MODELS

The quality models constitute layered approach (Table

I). The number of layers may be. 2 (Mc Call and Boehm)

or 3 layers (include metric). In Table I, 1:n relationships

show that every characteristics has its own sub-

characteristics (as in ISO 9126-1 model) and n:m

relationships show that every characteristic is linked to one

or more characteristics (as in Mc Call Factor-Criteria

Model (FCM)). In summary, various characteristics affect

the quality models that are represented in Table II. The

comparative analysis of characteristics of various software

quality models is also given in Table III.

IV. CONCLUSION

This is a comprehensive study to enumerate different

characteristics of various software qualitative models and

estimate their comparative viability. It is considered that

successful completion of this study will definitely help the

users to understand the quality factors properly. It will also

help estimation of software quality, identification and

definitions of the quality criteria in desired manner. Users

will also be able to realize the importance and role of the

quality models in estimating software quality.

Simultaneously, the different models which have been used

to evaluate the quality will be analyzed properly.



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TABLE I. LAYERED APPROACH OF QUALITY MODELS

TABLE II.

CHARACTERISTICS DEFINITION

Characteristics Definitions Ref.

Accuracy The capability of the software product to provide the right or agreed results or effects with the needed degree of precision. [18]

Availability The degree to which a work is operational and available for use as a product or to users [10]

Changeability The characterization of the amount of effort to change a system. [23]

Correctness The ease with which minor defects can be corrected between major releases while the application or component is in use by

its users.

[10]

Efficiency The capability of the software product to provide appropriate performance, relative to the amount of resources used understated conditions.

[18]

Flexibility The effort required modifying an operational program. [13]

Functionality The capability of the software product to provide functions meet stated and implied needs when the software is under

specified conditions.

[18]

Interface facility The degree to which two software products can be connected successfully. [10]

Integrity The extent to which access to software or data by unauthorized persons can be controlled. [13]

Interoperability The capability of the software product to interact with one or more specified systems. [18]

Maintainability The capability of the software product to be modified. [18]

Modifiability Corrections, improvements or adaptations of the software to changes in environment and in requirements and functional

specifications.

[18]

Performance The degree to which timing characteristics are adequate. [10]

Portability The capability of the software product to be transferred from one environment to another. [18]

Reliability The capability of the software product to maintain a specified level of performance when used under specified conditions. [18]

Reusability The ease with which an existing application or component can be reused. [10]

Robustness The degree to which an executable work product continues to function properly under abnormal conditions or circumstances.

[10]

Scalability The ease with which an application or component can be modified to expand its existing capabilities. [10]

Supportability The ability to extend the program, adaptability and serviceability, in addition to testability, computability, configurability,

the ease with which a system can be installed and the ease with which problems can be localized.

[32]

Testability The capability of the software product to enable modified software to be validated. [18]

Transferability The cost of transferring a product from its hardware or operational environment to another. [10]

Understandability The capability of the software product to enable the user to understand whether the software is suitable and how it can be

used for particular tasks and conditions of use.

[18]

Usability The capability of the software product to be understood learned, used and attractive to the user, when used under specified

conditions.

[18]

Layer Mc-

Call

[31]

Boehm

[4]

FURPS

[15]

Ghezzi et al.

[14]

IEEE

[17]

Dromey

[9]

ISO-9126-1

[18]

Kazman [25] Khosravi K. et

al. [28]

1 Factor High Level

characteristic

Characteristics Characteristics Factor Attribute Characteristic

Characteristics Super-

Characteristics

2 Criteria Primitive

characteristic

Sub-

characteristics

Sub-

characteristics

Sub-

factor

Sub-

attribute

Sub -

characteristic

Sub-

characteristics

Sub-

characteristics

3 n:m n:m 1:n 1:n 1:n n:m 1:n 1:n n:m



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TABLE III

COMPARISON OF QUALITY MODELS

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Mc

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m

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al. [14]

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Process Maturity X

Reusability X X X X

Robustness X

Scalability X

Security X X

Supportability X

Testability X X X

Understandability X X

Usability X X X X X X X X X X



119

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Comparison of Software Quality Models - An Analytical Approach

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