handout 3

* Property of STI of 14

Software Process and Project Metrics

I0065

Software Metrics

Software Metrics Definition

Measures, Metrics, and Indicators

Process and Project Indicators

Process Metrics

Project Metrics

Software Measurement

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* Property of STIPage 3 of 14


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Measures, Metrics, and Indicators

a measure provides a quantitative indication of the extent, amount, dimensions, capacity, or size of some attribute of a product or process

a metric is a quantitative measure of the degree to which a system, component, or process possesses a given attribute

an indicator is a metric or combination of metrics that provide insight into the software process, a software project, or the project itself; it provides insight that enables the project manager or software engineers to adjust the process, the project, or the product to make things better

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Software Metrics

refer to a broad range of measurements for computer software

measurement can be applied to the software process with the

intent of improving it on a continuous basis used throughout a software project to

assist in estimation, quality control, productivity assessment, and project control

used by software engineers to help assess the quality of technical work products and to assist in tactical decision making as a project proceeds

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Process and Project Indicators

Process indicators enable a software engineering organization to

gain insight into the efficacy of an existing process

Project indicators enable a software project manager to

1. assess the status of an ongoing project, 2. track potential risks, 3. uncover problem areas before they go

critical, 4. adjust work flow or tasks, 5. evaluate the project team’s ability to

control quality software engineering work products

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Process Metrics

Determinants for software quality and organizational effectiveness

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Project Metrics

Twofold intent of project metrics these metrics are used to minimize the

development schedule by guiding the adjustments necessary to avoid delays and mitigate potential problems and risks

project metrics are used to assess product quality on an ongoing basis and when necessary, modify the technical approach to improve quality

Suggested project measures inputs — measures of the resources

required to do the work outputs — measures of the deliverables or

work products created during the software engineering process

results — measures that indicate the effectiveness of the deliverables

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considered as tactical used by a project manager and a software

team to adapt project work flow and technical activities

its first application on most software projects occurs during estimation

metrics collected from past projects are used as a basis from which effort and time duration estimates are made for current software work

production rates represented in terms of pages of documentation, review hours, function points, and delivered source lines are measured

technical metrics are collected to assess design quality and to provide indicators that will influence the approach taken to code generation and module and integration testing

Project Metrics

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Direct Measures in software engineering process, it includes

cost and effort applied in product, it includes lines of code (LOC)

produced, execution speed, memory size, and defects reported over some set period of time

Indirect Measures include functionality, quality, complexity,

efficiency, reliability, maintainability, and many other “abilities”

Software Measurement

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Size-Oriented Metrics

derived by normalizing quality and/or productivity measures by considering the “size” of the software that has been produced

not universally accepted as the best way to measure the process of software development

Project LOC Effort P(000) pp.doc. Errors Defects People

alphabetagamma

.

.

.

.

12,10027,20020,200

.

.

.

.

246243....

168440314

.

.

.

.

36512241050

.

.

.

.

134321256

298664

356

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Function-Oriented Metrics

Information Domain Values Number of user inputs - each user input

that provides distinct application-oriented data to the software is counted

Number of user outputs - each user output that provides application-oriented information to the user is counted

Number of user inquiries - each distinct inquiry is counted

Number of files - each logical master file (i.e., a logical grouping of data that may be one part of a large database or a separate file), is counted

Number of external interfaces - all machine readable interfaces (e.g., data files on tape or disk) that are used to transmit information to another system are counted

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use a measure of the functionality delivered by the application as a normalization value

were first proposed by Albrecht, who suggested a measure called the function point

Function Point derived using an empirical relationship based

on countable (direct) measures of software’s information domain and assessments of software complexity

computed by completing the table shown below:


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To compute function points (FP), the following relationship is used:

FP = count-total x [0.65 + 0.01 x å Fi]

where count-total is the sum of all entries obtained from the figure.

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Software Quality Measures

Correctness the degree to which the software performs its

required function can be measured in defects per KLOC, where a

defect is defined as a verified lack of conformance to requirements

Maintainability the ease with which a program can be

corrected if an error is encountered, adapted if its environment changes, or enhanced if the customer desires a change in requirements

can be measured using MTTC (mean-time-to-change)

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Software Quality Measures

Integrity measures a system’s ability to withstand

attacks (both accidental and intentional) on its security

can be measured in terms of threat and security

Usability an attempt to quantify “user friendliness” and

can be measured in terms of four characteristics:

1) the physical and/or intellectual skill required to learn the system

2) the time required to become moderately efficient in the use of the system

3) the net increase in productivity measured when the system is used by someone who is moderately efficient

4) a subjective assessment of users attitudes toward the system

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handout 3

Design