Measurement Principles
19.2.2 Measurement Principles
Before we introduce a series of technical metrics that (1) assist in the evaluation of the analysis and design models, (2) provide an indication of the complexity of pro- cedural designs and source code, and (3) facilitate the design of more effective test- ing, it is important to understand basic measurement principles. Roche [ROC94] suggests a measurement process that can be characterized by five activities:
• ? Formulation. The derivation of software measures and metrics that are
What are
the steps of
appropriate for the representation of the software that is being considered.
an effective measurement
• Collection. The mechanism used to accumulate data required to derive the
process?
formulated metrics. • Analysis. The computation of metrics and the application of mathematical tools.
2 A vast literature on software metrics (e.g., see [FEN94], [ROC94], [ZUS97] for extensive bibliogra- phies) has been spawned, and criticism of specific metrics (including some of those presented in this chapter) is common. However, many of the critiques focus on esoteric issues and miss the primary objective of measurement in the real world: to help the engineer establish a systematic and objective way to gain insight into his or her work and to improve product quality as a result.
PA R T T H R E E C O N V E N T I O N A L M E T H O D S F O R S O F T WA R E E N G I N E E R I N G
• Interpretation. The evaluation of metrics results in an effort to gain insight into the quality of the representation.
• Feedback. Recommendations derived from the interpretation of technical metrics transmitted to the software team.
The principles that can be associated with the formulation of technical metrics are [ROC94]
• ? The objectives of measurement should be established before data collection
What rules
should we
begins.
observe when we
• Each technical metric should be defined in an unambiguous manner.
establish technical measures?
• Metrics should be derived based on a theory that is valid for the domain of application (e.g., metrics for design should draw upon basic design concepts and principles and attempt to provide an indication of the presence of an attribute that is deemed desirable).
• Metrics should be tailored to best accommodate specific products and processes [BAS84].
Although formulation is a critical starting point, collection and analysis are the activ- ities that drive the measurement process. Roche [ROC94] suggests the following prin- ciples for these activities:
Above all, keep your • Whenever possible, data collection and analysis should be automated. early attempts at
• Valid statistical techniques should be applied to establish relationships technical measurement
between internal product attributes and external quality characteristics (e.g., simple. Don’t obsess
over the “perfect” is the level of architectural complexity correlated with the number of defects metric because it
reported in production use?). doesn’t exist.
• Interpretative guidelines and recommendations should be established for each metric.
In addition to these principles, the success of a metrics activity is tied to management support. Funding, training, and promotion must all be considered if a technical mea- surement program is to be established and sustained.
Parts
» The Concurrent Development Model
» SUMMARY Software engineering is a discipline that integrates process, methods, and tools for
» PEOPLE In a study published by the IEEE [CUR88], the engineering vice presidents of three
» THE PROCESS The generic phases that characterize the software process—definition, development,
» THE PROJECT In order to manage a successful software project, we must understand what can go
» METRICS IN THE PROCESS AND PROJECT DOMAINS
» Extended Function Point Metrics
» METRICS FOR SOFTWARE QUALITY
» INTEGRATING METRICS WITHIN THE SOFTWARE PROCESS
» METRICS FOR SMALL ORGANIZATIONS
» ESTABLISHING A SOFTWARE METRICS PROGRAM
» Obtaining Information Necessary for Scope
» An Example of LOC-Based Estimation
» QUALITY CONCEPTS 1 It has been said that no two snowflakes are alike. Certainly when we watch snow
» SUMMARY Software quality assurance is an umbrella activity that is applied at each step in the
» R diagram 1.4 <part-of> data model; data model <part-of> design specification;
» SYSTEM MODELING Every computer-based system can be modeled as an information transform using an
» Facilitated Application Specification Techniques
» Data Objects, Attributes, and Relationships
» Entity/Relationship Diagrams
» Hatley and Pirbhai Extensions
» Creating an Entity/Relationship Diagram
» SUMMARY Design is the technical kernel of software engineering. During design, progressive
» Data Modeling, Data Structures, Databases, and the Data Warehouse
» Data Design at the Component Level
» A Brief Taxonomy of Styles and Patterns
» Quantitative Guidance for Architectural Design
» Isolate the transform center by specifying incoming and outgoing
» SUMMARY Software architecture provides a holistic view of the system to be built. It depicts the
» The User Interface Design Process
» Defining Interface Objects and Actions
» D E S I G N E VA L U AT I O N
» Testing for Real-Time Systems
» Organizing for Software Testing
» Criteria for Completion of Testing
» The Transition to a Quantitative View
» The Attributes of Effective Software Metrics
» Architectural Design Metrics
» Component-Level Design Metrics
» SUMMARY Software metrics provide a quantitative way to assess the quality of internal product
» Encapsulation, Inheritance, and Polymorphism
» Identifying Classes and Objects
» The Common Process Framework for OO
» OO Project Metrics and Estimation
» Event Identification with Use-Cases
» SUMMARY Object-oriented analysis methods enable a software engineer to model a problem by
» Partitioning the Analysis Model
» Designing Algorithms and Data Structures
» Program Components and Interfaces
» SUMMARY Object-oriented design translates the OOA model of the real world into an
» Testing Surface Structure and Deep Structure
» Deficiencies of Less Formal Approaches 1
» What Makes Cleanroom Different?
» Design Refinement and Verification
» SUMMARY Cleanroom software engineering is a formal approach to software development that
» Structural Modeling and Structure Points
» Describing Reusable Components
» SUMMARY Component-based software engineering offers inherent benefits in software quality,
» Guidelines for Distributing Application Subsystems
» Middleware and Object Request Broker Architectures
» An Overview of a Design Approach
» Consider expert Web developer will create a complete design, but time and cost can be appropriate
» A Software Reengineering Process Model
» Reverse Engineering to Understand Data
» Forward Engineering for Client/Server Architectures
» SUMMARY Reengineering occurs at two different levels of abstraction. At the business level,
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