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Metrics. "A science is as mature as its measurement tools." -- Louis Pasteur. Starter Questions. What can we measure? What value can those numbers have?. Why Measure?. accurate estimation how productive are we quality improvement what do we do well

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metrics

Metrics

"A science is as mature

as its measurement tools."

-- Louis Pasteur

starter questions
Starter Questions
  • What can we measure?
  • What value can those numbers have?
why measure
Why Measure?
  • accurate estimation
    • how productive are we
  • quality improvement
    • what do we do well
    • what do we do poorly
types of metrics
Types of Metrics
  • Product Metrics
    • direct measures - number of bugs, LOC
    • indirect measures - usability, maintainability
  • Project and Process Metrics
    • direct measures - costs, LOC per month
    • indirect measures - quality assurance, reliability
code metrics
Code Metrics
  • Size
    • Lines of Code
    • Function Points
  • Efficiency
    • BigO
  • Complexity
    • Cyclomatic Complexity
    • Halstead's complexity metrics (next slide)
  • Maintainability
halstead s complexity metrics
Halstead's Complexity Metrics

n1 = the number of distinct operators

n2 = the number of distinct operands

N1 = the total number of operators

N2 = the total number of operands

Program length N = N1 + N2

Program vocabulary n = n1 + n2

Volume V = N * (LOG2 n)

Difficulty D = (n1 / 2) * (N2 / n2)

Effort E = D * V

mccall s quality factors
McCall's Quality Factors

Portability

Reusability

Interoperability

Maintainability

Flexibility

Testability

Product

Revision

Product

Transition

Product Operations

Correctness

Reliability

Efficiency

Integrity

Usability

slide8
Operability

Training

Communicativeness

Input/Output volume

Input/Output gate

Access Control

Access Audit

Storage efficiency

Execution Efficiency

Traceability

Completeness

Accuracy

Error Tolerance

Consistency

Simplicity

Conciseness

Instrumentation

Expandability

Generality

Self-Descriptiveness

Modularity

Machine Independence

Software System Independence

Communications Commonality

Data Commonality

Usability

Integrity

Efficiency

Correctness

Reliability

Maintainability

Testability

Flexibility

Reusability

Portability

Interoperability

iso 9126 quality characteristics and guidelines for their use
ISO 9126 Quality Characteristics and Guidelines for Their Use

Quality Factors

  • Functionality
  • Reliability
  • Usability
  • Efficiency
  • Maintainability
  • Portability
design metrics
Design Metrics
  • Fan In
  • Fan Out
  • Morphology
      • based on number of nodes, depth, width
module design metrics
Module Design Metrics
  • Cohesion
      • how many functions does a module perform
        • coincidental
        • logical - eg does all output
        • temporal - eg all the startup work
        • procedural - executed in this order
        • communicational - module arrangement on work on what data
        • functional
  • Coupling
      • how is the module connected to other modules
        • global variable, parameters, stands alone
object oriented metrics
Object-Oriented Metrics
  • Weighted Methods per Class
      • not only how many methods per class are there, but also how complex are they
  • Depth of Inheritance Tree
  • Number of Children
      • how many child classes does a class have
  • Response for Class
      • number of local methods, plus number of methods they call
  • Lack of Cohesion Metric
      • number of non-intersecting (don't use the same variables) methods
lack of cohesion example
Lack of Cohesion Example
  • Module A calls Module B
  • B accesses Variable X
  • C and D access Y
  • D calls E
  • This should be split into two classes.

A

C

D

B

E

Y

X

project metrics
Project Metrics
  • LOC or FP per month
  • Errors per LOC (aka Defect Density)
  • Defect Removal Efficiency
  • Time required to make changes
  • Test coverage
  • Required Skills
obviously beware of statistics
Obviously,Beware of Statistics

Version 2 Version 1

Module# Defects LOC Defects/LOC Defects LOC Defects/LOC Relation

1 12 777 0.01544 3 55 0.05455 <

2 5 110 0.04545 6 110 0.05455 <

3 2 110 0.01818 3 110 0.02727 <

4 3 110 0.02727 4 110 0.03636 <

5 6 1000 0.00600 70 10000 0.00700 <

Sum 28 2107 0.01329 86 10385 0.00828 >

http://irb.cs.tu-berlin.de/~zuse/sme.html

basic questions
Basic Questions
  • What are the basic metrics that managers need to track?
  • How do we gather all these numbers?
  • When do we process all these numbers?
sei cmm level 2 repeatable
SEI CMM Level 2 (repeatable)
  • Software Requirements Management
      • status of allocated requirements
      • number of changes to requirements
  • Software Project Planning
      • completion of milestones compared to the plan
      • work completed, funds expended, … compared to plan
  • Software Project Tracking and Oversight
      • resources expended to conduct oversight
sei cmm level 3 defined
SEI CMM Level 3 (defined)
  • Training Program
    • number of training waivers approved
    • actual attendance vs projected attendance
    • results on post-training tests
  • Software Product Engineering
    • numbers, types, and severity of defects by stage
    • effort to analyze proposed changes
    • number of changes by category
summary
Summary

To do something well, we must understand what we are doing. To understand something, we must be able to measure it.

We can measure what we are building and we can measure our building process.

next topics
Next Topics…
  • Managing the testing process
  • Configuration Management
  • Exam #2