presents the COnstructive COst MOdel (COCOMO): the most advanced, thoroughly calibrated software cost estimation model available today.

Transcription

1 SOFTWARE ENGINEERING ECONOMICS BARRY W. BOEHM SUMMARY The primary learning objectives of Software Engineering Economies by Barry W. Boehm are to: identify the factors most strongly influencing software costs and use them to determine the estimated costs of a software project; understand the concepts of microeconomics as they apply to software engineering; and apply economic analysis techniques to software engineering decision situations. Among its special features, the book explains the fundamental concepts of microeconomics and demonstrates thelr utility through a practical, singlethread software engineering example. presents the COnstructive COst MOdel (COCOMO): the most advanced, thoroughly calibrated software cost estimation model available today. provides extensive case-study examples of the use of the COCOMO model for software life-cycle cost-benefit analysis and for software project planning and control. CONTENTS PREFACE xix PART I INTRODUCTION: MOTIVATION AND CONTEXT 1 Chapter 1 Case Study 1: Scientific American Subscription Processing The Old System The Programming Solution: Top-Down Stepwise Refinement The Programming Solution: Results The Economic-Programming Approach Results of the Economic-Programming Approach General Discussion Questions 8 Chapter 2 Case Study 2: An Urban School Attendance System Programming Aspects Economie Aspects Ruman Relations Aspects Lessons Learned General Discussion Questions 13 Chapter 3 The Goals of Software Engineering Introduction Software Engineering: A Definition Software Trends: Cost 17

2 3.4 Software Trends: Social Impact The Plurality of Goals An Examp1e: Weinberg's Experiment The Plurality of Software Engineering Means The Software Engineering Goal Structure The GOALS Approach to Software Engineering Questions 26 PART Il THE SOFTWARE LIFE-CYCLE: A QUANTITATIVE MODEL 29 Chapter 4 The Software Life-Cycle: Phases and Activities Introduction The Waterfall Model Economie Rationale for the Waterfall Model Refinements of the Waterfall Model Detailed Life-Cycle Phase Definitions Detailed Phase- Activity Definitions The Software Work Breakdown Structure (WBS) Software Maintenance Questions 55 Chapter 5 The Basic COCOMO Model Introduction Definitions and Assumptions Development Effort and Schedule Phase Distribution Nominal Project Profiles The Rayleigh Distribution Interpolation Basic Software Maintenance Effort Estimation Questions 71 Chapter 6 The Basic COCOMO Model: Development Modes Introduction Basic Effort and Schedule Equations The Three COCOMO Modes of Software Development Discussion of the Basic COCOMO Effort and Schedule Equations Phase Distribution of Effort and Schedule Questions 94 Chapter 7 The Basic COCOMO Model: Activity Distribution Introduction Activity Distribution by Phase Basic COCOMO Case Study: The Hunt National Bank EFT System Deriving Basic Project Organization Charts Discussion of Basic COCOMO Phase and Activity Distributions Limitations of Basic COCOMO Questions 111 Chapter 8 The Intermediate COCOMO Model: Product Level Estimates Introduction Intermediate COCOMO: Software Development Effort Estimation A Pricing Example: Microprocessor Communications Software A Management Example: Reduced Cost-to-Complete Adjusted Estimate of Annual Maintenance Effort Example: Microprocessor Communications Software Maintenance Interpolation and Extrapolation Estimating the Effects of Adapting Existing Software Discussion of the Intermediate COCOMO Effort Equations Questions 141 Chapter 9 Intermediate COCOMO: Component Level Estimation Introduction The Component Level Estimating Form (CLEF) Using the CLEF with Adapted Software Transaction Processing System (TPS) Example: Basic Development Estimate TPS Component Level Maintenance Estimate and Phase Distribution 156

3 9.6 Questions 160 PART III FUNDAMENTALS OF SOFTWARE ENGINEERING ECONOMICS 165 PART IlIA COST-EFFECTIVENESS ANALYSIS 169 Chapter 10 Performance Models and Cost-Effectiveness Models Performance Models Optimal Performance Sensitivity Analysis Cost-Effectiveness Models Questions 181 Chapter 11 Production Functions: Economies of Scale Example General Discussion: Definitions Discrete Production Functions Basic Production Functions for Software Development Economies and Diseconomies of Scale Diseconomies of Scale on Large Software Projects The Best Way to Combat Diseconomies of Scale Questions 195 Chapter 12 Choosing Among Alternatives: Decision Criteria Example: Minimum Available Budget Minimum Performance Requirement Maximum Effectiveness-Cost Ratio Maximum Effectiveness-Cost Difference Composite Options General Discussion Questions 202 PART IIIB MULTIPLE-GOAL DECISION ANALYSIS 205 Chapter 13 Net Value and Marginal Analysis Example General Discussion: Marginal Analysis Illustration Sorne Caveats in Dealing with Net Value and Profit Value of Information Processing Products Questions 213 Chapter 14 Present versus Future Expenditure and Income Example: An Oversimplified Cost Analysis Interest Calculations Present Value Calculations Present Value of a Series of Cash Flows Summary of Rental versus Purchase Analysis General Discussion: Summary of Present Value Concepts and Formulas Present Value Characteristics Sensitivity to Interest Rate or Discount Rate Applications to Software Engineering Questions 221 Chapter 15 Figures of Merit Example: Software Package Selection Net Value Analysis Figure of Merit Analysis General Discussion: A Weighted Sum Analysis for Hardware and Software Selection: A Case Study Case Study: Activity Description Case Study: Problems with the Evaluation Function Case Study: Problems with Weights and Ratings Case Study: Summary The Delivered System Capability (DSC) Figure of Merit Properties of the DSC Figure of Merit The TPS Example Revisited 238

4 15.12 Comparison of Weighted-Sum and DSC Figures of Merit Questions 241 Chapter 16 Goals as Constraints Example: TPS Option A Failure Modes System Reliability and A vailability Figure of Merit Evaluation Expressing Goals as Constraints Goals as Constraints: Feasible Sets and Cost-Value Contours General Discussion: Decision Problems with Constraints Software Engineering Applications Mathematical Optimization Techniques Capabilities and Limitations of Mathematical Optimization Techniques Questions 256 Chapter 17 Systems Analysis and Constrained Optimization Example General Discussion Questions 263 Chapter 18 Coping with Unreconcilable and Unquantifiable Goals Example: TPS Option B: Special-Purpose Operating System Development In-House versus Vendor Development Considerations Presentation Methods General Discussion: Unquantifiable Criteria Presentation Techniques for Unquantifiable Criteria Presentation Techniques for Mixed Quantifiable and Unquantifiable Criteria Some Cautions in Presenting and Interpreting Multivariate Data Questions 276 PART IIIC DEALING WITH UNCERTAINTIES, RISK, AND THE VALUE OF INFORMATION 278 Chapter 19 Coping with Uncertainties: Risk Analysis Example: Operating System Development Options Decision Rules for Complete Uncertainty Subjective Probabilities General Discussion: Decision Rules Under Complete Uncertainty The Value of Information Subjective Probabilities Utility Functions Software Engineering Implications Questions 286 Chapter 20 Statistical Decision Theory: The Value of Information Example: The Prototype Approach Expected Value of Perfect Information Working with Imperfect Information Example Bayes' Formula Maximizing the Net Expected Value of the Prototype General Discussion: Expected Value of Perfect Information Expected Value of Imperfect Information The Value-of-Information Procedure Use of the Value-of-Information Procedure in Software Engineering Value-of-Information Decision Guidelines PitfaIIs Avoided by Using the Value-of-Information Approach Value of Information: Wrap-Up Questions 300 PART IV THE ART OF SOF1WARE COST ESTIMATION 305 PART IVA SOF1WARE COST ESTIMATION METHODS AND PROCEDURES 308 Chapter 21 Seven Basic Steps in Software Cost Estimation Step 1: Establish Objectives Step 2: Plan for Required Data and Resources Step 3: Pin Down Software Requirements 315

5 21.4 Step 4: Work Out as Much Detail as Feasible Step 5: Use Several Independent Techniques and Sources Step 6: Compare and Iterate Estimates Step 7: FoIIowup Questions 328 Chapter 22 Alternative Software Cost Estimation Methods AIgorithmic Models Expert Judgment Estimation by Analogy Parkinsonian Estimation Price-to-Win Estimating Top-Down Estimating Bottom-Up Estimating Summary Comparison of Methods Questions 342 PART IVB THE DETAILED COCOMO MODEL 344 Chapter 23 Detailed COCOMO: Summary and Operational Description Introduction The Software Hierarchy Estimating Form (SHEF) The Software Hierarchy Estimating Form (SHEF) Procedures Detailed COCOMO Example: Student Job Information System Schedule Adjustment Calculations Discussion Questions 367 Chapter 24 Detailed COCOMO Cost Drivers: Product Attributes RELY: Required Software Reliability DATA: Data Base Size CPLX: Software Product Complexity Questions Topics of Research 397 Chapter 25 Detailed COCOMO Cost Drivers: Computer Attributes TIME: Execution Time Constraint STOR: Main Storage Constraint VIRT: Virtual Machine Volatility TURN: Computer Turnaround Time Questions Topics for Further Research 424 Chapter 26 Detailed COCOMO Cost Drivers: Personnel Attributes ACAP: Analyst Capability AEXP: Applications Experience PCAP: Programmer Capability VEXP: Virtual Machine Experience LEXP: Programming Language Experience General Discussion of Personnel Attributes Questions Topics for Further Research 449 Chapter 27 Detailed COCOMO Cost Drivers: Project Attributes MODP: Modem Programming Practices TOOL: Use of Software Tools SCED: Schedule Constraint Questions Topics for Further Research 473 Chapter 28 Factors Not Included in COCOMO Type of Application Language Level Other Size Measures: Complexity, Entities, Specifications Requirements Volatility Personnel Continuity Management Quality 486

6 28.7 Customer Interface Quality Amount of Documentation Hardware Configuration Security-Privacy Restrictions Topies for Further Research 490 Chapter 29 COCOMO Evaluation Introduction The COCOMO Project Data Base COCOMO Estimates versus Actuals: Development Effort COCOMO Estimates versus Actuals: Development Schedule COCOMO Estimates versus Actuals: Phase Distribution COCOMO Estimates versus Actuals: Activity Distribution Other Software Cost-Estimation Models COCOMO Evaluation with Respect to Model Criteria Tailoring COCOMO to a Particular Installation Topics for Further Research 530 PART IVC SOFTWARE COST ESTIMATION AND LIFE-CYCLE MANAGEMENT 532 Chapter 30 Software Maintenance Cost Estimation Introduction The COCOMO Software Maintenance Model Comparison with Project Results Other Software Maintenance Cost-Estimation Models Software Maintenance Phenomenology Software Maintenance Project Data Questions Topics for Further Research 554 Chapter 31 Software Life-Cycle Cost Estimation Introduction Software Conversion Cost-Estimating Relationships Software Conversion Estimates versus Actuals Software Installation and Training Cost Estimation Computer Cost Estimation for Software Development Amount of Software Documentation Other Software- Related Life-Cycle Costs An Example Software Life-Cycle Cost-Benefit Analysis Topics for Further Research 590 Chapter 32 Software Project Planning and Control Introduction A Software Project Planning and Control Framework Project Scheduling Techniques Detailed Software Planning and Control: The Unit Development Folder Monitoring Project Expenditures versus Progress: The Eamed Value System Software Project Planning and Control Example Building a Software Cost Data Base Software Planning and Control: Summary Discussion Questions 638 Chapter 33 Improving Software Productivity Introduction Non-Programming Options: Software Packages Non-Programming Options: Program Generators Software Productivity Controllables: Product Attributes Software Productivity Controllables: Computer Attributes Software Productivity Controllables: Personnel Attributes Software Productivity Controllables: Project Attributes Establishing a Software Productivity Improvement Program Conclusions 688 INDEX 751 TOP