Software Sizing, Estimation, And Risk Management: When Performance Is Measured Performance Improves

573 Pages·2006·11.301 MB·English

by  Daniel D. Galorath, Michael W. Evans

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Software Sizing,
Estimation, and
Risk Management
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Au3593_title 1/17/06 3:44 PM Page 1
Software Sizing,
Estimation, and
Risk Management
When Performance is Measured
Performance Improves
Daniel D. Galorath • Michael W. Evans
Forewords by Dr. Barry Boehm & Donald Reifer
Boca Raton New York
AU3593_Discl.fm Page 1 Monday, December 19, 2005 2:26 PM
Published in 2006 by
Auerbach Publications
Taylor & Francis Group
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Boca Raton, FL 33487-2742
© 2006 by Taylor & Francis Group, LLC
Auerbach is an imprint of Taylor & Francis Group
No claim to original U.S. Government works
Printed in the United States of America on acid-free paper
10 9 8 7 6 5 4 3 2 1
International Standard Book Number-10: 0-8493-3593-0 (Hardcover)
International Standard Book Number-13: 978-0-8493-3593-8 (Hardcover)
Library of Congress Card Number 2005058144
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Library of Congress Cataloging-in-Publication Data
Galorath, Daniel D.
Software sizing, estimation, and risk management : when performance is measured performance
improves / Daniel D. Galorath, Michael W. Evans.
p. cm.
Includes bibliographical references and index.
ISBN 0-8493-3593-0 (alk. paper)
1. Computer software--Development. 2. Risk management. I. Evans, Michael W. II. Title.
QA76.76.D47G347 2006
005.1--dc22 2005058144
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Dedication
Dan Galorath dedicates this book to my wife
Judy Galorath
who is an inspiration in all areas of my life and without whom this
book may have never gotten finished.
Mike Evans dedicates this book to the memory of
Elliot Needleman
“A Friend, a Mentor and a Heck of a Good Guy”

Contents
Foreword: Under the Tip of the Estimation Iceberg by Barry Boehm....xvii
Foreword by Donald J. Reifer.......................................................................xix
Preface............................................................................................................xxi
How This Book Came about from a Galorath Viewpoint....................xxi
Audience..................................................................................................xxiii
Structure of the Book..............................................................................xxv
What Can You Expect from the Book?..................................................xxv
Acknowledgments.......................................................................................xxvii
The Authors..................................................................................................xxix
1 The Problem.................................................................................1
Introduction.......................................................................................................1
Focus of the Book............................................................................................4
Why Software Projects Fail..............................................................................4
Why Software Projects Fail: Problems with Estimation.................................7
Why Software Projects Fail: Size Estimates....................................................9
Why Estimates Fail..........................................................................................13
Historical Data.................................................................................................14
Overly Optimistic Leadership and Management..........................................16
Failure to Use Estimate..............................................................................16
Failure to Keep Estimate Current.............................................................18
Role of Risk Management in Estimating.......................................................18
The Solution: Software Estimation — Ten-Step Process.............................20
Summary..........................................................................................................21
Endnotes....................................................................................................................21
2 Introduction to Software Estimation Techniques and
Estimate Planning.......................................................................25
Introduction and Chapter Goals....................................................................25
Need for Efficient Software Project Management Metrics...........................26
Core Metrics Categories..................................................................................28
vii
viii (cid:2) Software Sizing, Estimation, and Risk Management
Software Project Estimates: Foundations of Software Project
Management....................................................................................................30
Software Estimation Concepts........................................................................34
Project Estimation Process..............................................................................35
Step One: Establish Estimate Scope and Purpose..................................36
Step Two: Establish Technical Baseline, Ground Rules, and
Assumptions................................................................................................38
Step Three: Collect Data...........................................................................39
Underlying Information........................................................................39
Interview with Judy Galorath........................................................................45
Software Data Collection Process..................................................................48
Software Data Collection Lessons Learned...................................................50
Prioritizing Estimation Effort..........................................................................54
Summary..........................................................................................................54
Endnotes....................................................................................................................54
3 Executing the Estimate..............................................................57
Introduction and Chapter Goal......................................................................57
Step Four: Software Sizing.............................................................................57
Predicting Size............................................................................................58
Size Estimation Approaches......................................................................60
Deciding on a Metric.................................................................................61
When to Use SLOC...............................................................................63
When to Use Function Points..............................................................63
Steps to Estimating Software Size.............................................................64
Sizing Step 1: Baseline Definition of the Size Metric You Will Use...65
Sizing Step 2: Define Sizing Objectives..............................................65
Sizing Step 3: Plan Data and Resource Requirements.......................66
Sizing Step 4: Identify and Evaluate Software Requirements............66
Sizing Step 5: Use Several Independent Techniques and Sources...66
Sizing Step 6: Tracking.........................................................................68
Sizing Databases.........................................................................................68
Legacy Software Rework...........................................................................69
Sizing Number of Functions to Be Learned, Used, and Integrated
for COTS................................................................................................70
Step Five: Prepare Baseline Estimate............................................................70
Software Productivity Laws.......................................................................72
Bottom-Up Estimating................................................................................78
Software Cost Models................................................................................78
Organizing the Estimating Process...........................................................86
Delphi and Wideband Delphi...................................................................87
Activity-Based Estimates............................................................................89
Step Six: Quantify Risks and Risk Analysis..................................................99
Cost Estimation Risks.................................................................................99
Summary........................................................................................................102
Endnotes..................................................................................................................102
Contents (cid:2) ix
4 Planning and Controlling the Project via the Estimate.......105
Introduction...................................................................................................105
Step Seven: Estimate Validation and Review..............................................105
Estimate Review Process.........................................................................107
Estimate Review Activities.......................................................................108
Cost per Unit of Code Developed.........................................................109
Magic Bullets (Otherwise Known as Technical Leaps)...................109
Unrealistic Schedules..........................................................................110
Inaccurate Sizing.................................................................................110
Complexity versus Risk.......................................................................111
Careful Evaluation of Preexisting and COTS Software....................112
Off-the-Shelf Integration.....................................................................112
Function Point Counting Checklist.........................................................113
Sanity Counts.......................................................................................113
Lack of Convergence..........................................................................113
Double Counting.................................................................................113
Sample and Statistical Concerns........................................................114
Probability Level..................................................................................114
Falsely Bounded Risk.........................................................................114
Costs..........................................................................................................115
Are Staff Costs Fully Burdened?.........................................................115
How Many Hours Are in a Staff Month?..........................................115
Staff and Effort Accounting.....................................................................115
Does Overtime Count?........................................................................115
What Level of Management Participates?..........................................115
How Efficiently Is Staff Allocated?.....................................................116
Are Experience Levels Honestly Rated?............................................116
Schedules..................................................................................................116
What Is the Proportion of Daily Billable Work Done?....................116
Will Development Have Lags?...........................................................116
If Several Software Elements Are Developed, How Are They
Scheduled?...........................................................................................116
Is It More Important to Save Time or Staff Cost?............................117
Sanity Check........................................................................................117
Estimate Process Questionnaire...................................................................117
Step Eight: Generate Project Plan...............................................................128
Action Items by Project Phase................................................................129
Determining Costs from Effort Estimates...............................................133
Estimating Personnel Mix...................................................................133
Labor Proportions.....................................................................................134
Other Costs...............................................................................................134
Travel Costs.........................................................................................134
Personnel Costs...................................................................................134
Depreciation Costs..............................................................................137
Training Costs......................................................................................137