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NYCity SPIN Presentiation New York NY, May 2003. “Why Size Matters”. Michael C. Mah Managing Partner QSM Associates, Inc. 75 South Church Street Pittsfield, MA 01201 413-499-0988 Fax 413-447-7322 e-mail: [email protected]. Web Site: www.qsma.com. Ed Yourdon on “Sizing”. - PowerPoint PPT Presentation
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1QSM Associates, Inc.
Michael C. MahManaging Partner
QSM Associates, Inc.75 South Church Street
Pittsfield, MA 01201413-499-0988
Fax 413-447-7322e-mail:
“Why Size Matters”
Web Site: www.qsma.com
NYCity SPIN PresentiationNew York NY, May 2003
2QSM Associates, Inc.
3QSM Associates, Inc.
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“If you underestimate the size
of your next project, common
sense says that it doesn’t
matter which methodology you
use, what tools you buy, or
even what programmers you
assign to the job.”
Ed Yourdon on “Sizing”..
6QSM Associates, Inc.
Rifkin’s* Criteria:Estimation Processes
1) Commitments have to be based on work [scope] to be performed; therefore, there must be agreement on this
2) Estimates have to be based on a) the work to be performed and b) historical records of performance
3) Commitments must not exceed the capability to perform, or else there is no reason to estimate
* Stan Rifkin, Master Systems Inc.(formerly with Carnegie Mellon SEI)
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Sizing Has a Purpose
Productivity Measurement (Historical View)
Project Estimation (Future View)
Project Risk Tracking (Present View)
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Software Measurement and Management – 3
Key Areas
ProjectEstimation
“In-Flight”Tracking
Support FutureCommitments
ManageCommitmentCommitment
Analyze Performance on Commitment
ProjectHistory
Assess Viable Strategies
Monitor Status & ReplanPost Project Analysis
Make Commitment
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QSM Productivity Index (PI)(industry values by application type)
0 2 4 6 8 10 12 14 16 18 20 22 24
Productivity Index (PI) w/ ±1 Standard Deviation
Avionics
Business
Command and Control
Microcode
Process Control
Real Time
Scientific
System
Telecommunications
Information
Engineering
Real Time
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Example – Historical and New Project Assessment
Main Build Time vs. Size
1 10 100 1000
Months
1
10
100
SmartMed History QSM Industry Avg 1 Sigma Range
New + Modified Size
Project A history20 months
Project B history8.5 months
SmartMedDeadline – 6 months
SmartMed Schedule Target InconsistentWith History Trend
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Early Warning - Tracking Size for “In-Flight”
ProjectsSize
0
10
20
30
40
50
60
70
S 1 2 3 4 5 6 7 8S 1 2 3
ES
LOC
(thousands)
Oct'92
Jan'93
Apr Jul Oct Jan'94
Apr Jul Oct Jan'95
Apr Jul
Actual
Interpolated
Plan
Green CB
Yellow CB
S = Start
1 = HLD
2 = LLD
3 = UIT
4 = SIT
5 = SVT
6 = BT
7 = GA
8 = 99R
Size (ESLOC(K))PI 10.8 9.1 -1.7MBI 1.2 0.6 -0.6
Date 1/2/94 (14.1 mos)
Plan Actual Diff37.12 32.30 -4.82
Data are Consistentlyin the Amber Region
Example
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Cutter Consortium Study on Software Estimation
Source: Cutter Consortium, Benchmark Review Vol. 2, No. 8
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Perceptions of Size
Microsoft
Industry Leader?
Microsoft
Brutal Monopolist?
Different views aren’t necessarily crazy
None of us has sole possession of the truth
Not always Right/Wrong, more often a case of Right/Right
Function Points are a Savior
Function Points areEvil
Counting Code is Relevant
Counting Code is Stupid
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Ed Yourdon on “Sizing”..
“Studies by the Carnegie Mellon
SEI indicate that the most
common failing of
Level 1 (Ad-hoc) software
organizations is an inability to
make size estimates accurately.”
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The Common Obstacle to Software Sizing
“Never been asked to
consider size up front or
after the fact; always
equated size to effort i.e.
number of hours”
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Software Sizing
How do we Describethe Volume of Software?
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Many Functional Metrics Can be Used to Represent S/W Size
Subsystems
Entities
Function points
Modules
Objects
Programs
SLOC
Actions/Instructions/Statements
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Functional Metrics(Proxies)
They all represent what has to be created, but at different levels of abstraction
They all can be useful Knowing the scaling relationships, enables
us to use them effectively
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Size – Scaling Relationships
Objects 150 – 250 loc/Object Function Points 30 - 400 Modules 100 - 500 Programs 200 - 1400 Subsystems 4,000 - 12,000
Can Be Determined from Data
Typical Examples
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For Additional Information
Contact:
Michael MahManaging PartnerQSM Associates Inc.Clocktower Building75 So. Church St., Suite 600Pittsfield, MA 01201
Email: [email protected] url: www.qsma.com
