Software Project Estimation

The Fundamentals for Providing High Quality Information to Decision Makers

Alain Abran

• Publisher: Wiley-IEEE Computer Society Pr
• Year: 2015
• Print ISBN: 9781118954089
• eBook ISBN: 9781118959329
• Edition: 1
• Topic: Computer Science
• Subtopic: Project Management
• Index: Computer Science

This book introduces theoretical concepts to explain the fundamentals of the design and evaluation of software estimation models. It provides software professionals with vital information on the best software management software out there.

• End-of-chapter exercises
• Over 100 figures illustrating the concepts presented throughout the book
• Examples incorporated with industry data

Part I

Understanding the Estimation Process

Estimation is not at all about coming up with a magic number to which everyone must commit at the peril of their professional career (which leads to staff members spending lots of overtime attempting to meet unrealistic deadlines.)

Part 1 of this book consists of three chapters, in which some of the key concepts of an estimation process are introduced.

Chapter 1 introduces the estimation process, including:

• the collection of data to be input to the estimation process,
• their usage with a productivity model,
• the adjustment phase to handle project assumptions, uncertainties, and risks,
• the budgeting phase,
• the estimator role: to provide information on a range of estimates,
• the manager role: to select a specific budget from the range of estimates identified by the estimator.

Chapter 2 explains the relationship between the software development life process and the classic model of a process. A number of economics concepts are introduced and illustrated in the context of software projects, such as:

• economies and diseconomies of scale, and
• fixed and variable costs.

Chapter 3 discusses the impact of the selection of a single budget value from a range of estimates, including the identification of scenarios and their corresponding probabilities, and the identification and management of contingencies at the project portfolio level.

Chapter 1
The Estimation Process: Phases and Roles

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Objectives

This chapter covers

1. – Two generic approaches to estimation: judgment-based and engineering based
2. – An overview of the process for estimating software projects
3. – The foundation: The productivity model
4. – The phases of the estimation process
5. – Roles and responsibilities in estimating and budgeting

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1.1 Introduction

When an organization has not measured its own productivity on past projects, it is mostly in the dark about:

• how the organization is performing,
• how much a manager's performance differs from someone else's, and
• how much the assumptions made in a manager's estimation judgment differ from those made in someone else's!

In this context, which is typical in many software organizations, using productivity models originating in environments with different productivity performance ratios does not provide real value. This is all the more true when little is known about

• the quality of the data in these external repositories and
• the quality of the productivity models within the environments in which they have been built.

When an organization has collected its own data and developed its own set of capabilities for analyzing those data and documenting the quality of their productivity models, then it has developed

• a key competitive advantage in market-oriented organizations and
• a key credibility advantage in organizations in noncompetitive contexts.

Estimation is not at all about coming up with a magic number to which everyone must commit at the peril of their professional career (which leads to staff members spending lots of overtime attempting to meet unrealistic deadlines.)

This chapter presents an overview of the phases of an estimation process and explains the differences between a productivity model and its use in an estimation process. It is organized as follows:

• Section 1.2 introduces two generic approaches to estimation: judgment and engineering.
• Section 1.3 provides an overview of some common practices and expectations involved in estimating software projects.
• Section 1.4 discusses the levels of uncertainty in an estimation process.
• Section 1.5 presents the key concepts of a productivity model.
• Section 1.6 explains the use of a productivity model in an estimation process.
• Section 1.7 discusses the estimation responsibilities in a business context.
• Section 1.8 explains the differences between budgeting and pricing.
• Section 1.9 provides a summary of the chapter.

1.2 Generic Approaches in Estimation Models: Judgment or Engineering?

1.2.1 Practitioner's Approach: Judgment and Craftsmanship

In contrast to estimation with mathematical models, where explicit cost drivers are included in the models as either quantitative or categorical parameters, which are manipulated with well-described mathematical equations, the estimation technique often used in practice in industry (also referred to as the expert judgment estimation approach) would not typically document which parameters are taken into account, or how they are explicitly combined.

The overall estimation process in the expert judgment approach is similar to the estimation process described later in this chapter, but is much less transp...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• Foreword
• Overview
• Acknowledgments
• About the Author
• Part I: Understanding the Estimation Process
• Part II: Estimation Process: What Must be Verified?
• Part III: Building Estimation Models: Data Collection and Analysis
• References
• Index
• End User License Agreement