Spmm Topic 2

8/3/2019 Spmm Topic 2

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Software Process Management

and Metrics

Topic #2

Measurement


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Measurement

Motivation

No metric, no movement

You can neither predict nor

control what you cannot

measure2S. Bhatti, Software Process Management

and Metrics


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Measurement

What is measurement?

3S. Bhatti, Software Process Managementand Metrics


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Measurement

Measurement is the process by which number

or symbols are assigned to attributes of

entities (objects) in the real world in such a

way as to ascribe them according to defined

rules.


Objects Attributes Values

Attribute 1 Value 11 Value 12 Value 13Object Attribute 2 Value 21 Value 22 Value 23

Attribute n Value n1 Value n2 Value n3


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Measurement

It is wrong to say we measure an object or an

attribute

For example, it is wrong to say we measure a room or that

we measure height, from a measurement point of view,although we use such language in our daily lives all the

time

Then what is the proper way to say these things?



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Measurement

The height of a person is a commonly understood

attribute of a person, which can be measured. Can

intelligence of a person be measured?

Can we measure the height of a person in meters,inches or feet? Which is correct?

Can we measure the height of a person in miles

instead of feet or inches? If so why, if not why not?

It is meaningful to take the average height of a

football team. Why? Is it meaningful to take the

average of the jersey numbers of the team? Why?



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Measurement

Metricsstandards (i.e., commonly accepted

scales) that define measurable attributes of

entities, their units and their scopes.

For example, prices of clothing (number of Pak Rupees)

and sizes of clothing (XL, L, M, S)

Measureis a relationship between an

attribute and a measurement scale. For example, the height of a person and inches



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Measurement

Metrics Example


Entity Attribute

Requirement Size, Reuse, Redundancy

Specification Size, Reuse, Redundancy

Design Size, Reuse, Modularity,

Cohesion, Coupling

Code Size, Reuse, Modularity,

Cohesion, Coupling,

Complexity

Test Cases Size, Coverage

Metrics for Size

# of requirements

# of features

# of classes

# of lines of code (LOC)

# of test cases


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Measurement

Measurement Example: Developed Software



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Measurement

Measurement Example

1. Select entities: Developed Software

2. Select attributes: Size

3. Select metric for attributes: Number of LOC

4. Specify rules (relationships) ascribed to the

attributes and entities:

Developed Software = Developed Software t=0+ (Software Development Rate) dtWhere Software Development Rate = LOC/dt



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Measurement

Another Measurement Example

1. Select entities: Availability

2. Select attributes: Uptime, downtime

3. Select metric for attributes: time in seconds

4. Specify rules (relationships) ascribed to the

attributes and entities:

Availability = uptime / (uptime + downtime)



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Measurement

Challenges of Measurement in Software Engineering


Entity attribute value units

Physical Human Height 178 cm

Non-physical Human IQ 89 IQ index

Software Engineering metrics are mostly non-physical

Availability Reliability, Maturity, Portability, flexibility And relations are hard to quantify, but not hopeless!


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Measurement

Challenges of Measurement in Software Engineering


Metrics can be misleading

Fact 1: Knowledge is power

Fact 2: Time is money

Rule/Relationship:

power = work /time

The harder you work the more power you have

As power approaches infinity, time approaches 0

Substituting power and time

Knowledge = work/money

The less you know, the more you make!

As knowledge approaches zero, money approaches infinity


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Measurement

What does measurement in software

engineering help us do?



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Measurement

Measurement in software engineering help us understand,

control and improve:

The product

The people (control in a good way, i.e., productivity)

The technologies (for example, software configuration management)

The process

But

Measuring in software engineering is relatively new and

controversial

It is not yet clear which are the appropriate metrics for a

software project or whether people, processes, or products

can be compared using metrics



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Measurement

Measurement in software engineering entails

selecting, measuring and combining many different

attributes of:

Software products Software development resources

Software development technologies

Software development processes

This includes metrics which are directly measureable, such as

lines of code (LOC), as well as items which are calculated

from measurement, such as software quality.



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Measurement

Who benefits from measurement?



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Measurement

Managers

What does each step of the process cost?

How productive is the staff?

How good is the code that is being developed?

Will the user be satisfied with the project?

How can we improve?

Engineers

Are the requirements testable?

Have we found all the failures

Have we met our process or product goals What can we predict about our software product in the future

Users?



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Measurement

What is the scope of software metrics?



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Measurement

Scope of software metrics include:


Process

Product

People Technology


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Measurement

Scope of software metrics Cost effort estimation

Productivity measures and models

Data collection

Quality model and measures Reliability models and measures

Performance evaluation and models

Structural and complexity metrics

Capability maturity assessment

Management metrics

Evaluation Methods and tools



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Measurement

Scope of software metrics Cost effort estimation

Software cost estimation is the process of predicting

the amount of effort required to build a software

system Estimates for project cost and time requirements are

derived during the planning stage of the a project

Models used to estimate cost can be categorized as

either cost models (e.g., Constructive Cost ModelCOCOMO) or constraint models (e.g., Software Life

cycle Management SLIM) based on linear programming



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Measurement

Scope of software metrics Productivity measures and models

Productivity = size/effort, LOC/person month

Productivity model based on decomposition to measureable

attributes:


Productivity

Value

Quality

Reliability Defect

Quantity

Size Functionality

Cost

Personnel

Time Money

Resources

Hardware Software

Complexity

Constraints Difficulty


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Measurement

Scope of software metrics Data collection

Very critical and very hard step

1. What Data should be collected?

2. How it should be collected?

3. Is collected data reproducible?

Example: software failure data collection

1. Time of failure2. Time interval between failure

3. Cumulative failure up to a given time

4. Failures experienced in a time interval



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Measurement

Scope of software metrics Quality model and measures

McCalls quality factors



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Measurement

Scope of software metrics Reliability models and measures

Plot the change of failure intensity () against

time Models: basic exponential model and

logarithmic Poisson model

The basic exponential model assumes finite

failures in infinite time; the logarithmic Poisson

model assumes infinite failures



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Measurement

Scope of software metrics Reliability models



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Measurement

Scope of software metrics Performance evaluation and models

Using externally observable performance

characteristics such as response time andcompletion rate

Efficiency of algorithms (Big O Notation)



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Measurement

Scope of software metrics Structural and complexity metrics

Structural

Control flow structures

Data flow structures

Data structures

Information flow attributes

Complexity Cyclomatic complexity, that is, defining number of

independent paths in the execution of a program



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Measurement

Scope of software metrics Capability maturity assessment

Software Engineering Institute (SEI) model

CMMI: Level 1 trough Level 5

ISO 9001

Model for quality assurance in design/development,

production installation and servicing

ISO 9000-3 Guidelines for application of ISO 9001 to the

development, supply and maintenance of software



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Measurement

Scope of software metrics Management metrics

Metrics for project control

1. Metrics for requirements and specification

2. Metrics for the design model

3. Metrics for code

4. Metrics for testing

5. Schedule metrics

6. Resource metrics

7. Change metrics



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Measurement

Scope of software metrics Evaluation Methods and tools

Benchmarking

Certification Configuration management system

Requirements management system

Defect management system

Integrated Development Environment

Development Tool Chain



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Research

For Your Research. You will need to know

Process Modeling

System Dynamics The calculus underlying process dynamics

Rates and Levels

Software Process Modeling

Modeling and Simulation Tools



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Research

Topic #5 will formally introduce you to Process Modeling

Topics #6 will formally introduce you to software process

modeling AND give you a complete example (based on Brooks

claim) of what is expected from you for your research project

Topics #2 (today), #3 and 4 will introduce you to some

preliminary material on:

Process Modeling

System Dynamics

The calculus underlying process dynamics

Rates and Levels Software Process Modeling

Modeling and Simulation Tools



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Software Process


Research

Software Process

Software Project

Jan 1, 2011 Dec 31, 2012

RequirementsResources Product


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Another way to look at the Software Process


Research

Levels Rate


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Yet another way to look at the Software Process

37S Bhatti Software Process Management

Research

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FP/Day

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Rate: 1 FP/Day

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FP

Days

Level: Developed SW

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Requirement

Days

Level: Requirement

Rate SW = FP/Day

Rate SW * Day = FP

Rate Req = - Req/Day

Initial + (Rate Req * Day) = Req

Rate = Level/ time

Date post:	06-Apr-2018
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Spmm Topic 2

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