SoftwareEstimation1

Software Estimation Tiarra Kennedy: 

Software Estimation Tiarra Kennedy References: Jones, Capers. 2002. Software Cost Estimation in 2002. Cited 20 January 2003. Available from the World Wide Web: (http://www.stsc.hill.af.mil/crosstalk/2002/06/index.html) Henry, David. 2002. Software Estimation Perfect Practice Makes Perfect. Cited 20 January 2003. Available from the World Wide Web: (http://www.stsc.hill.af.mil/crosstalk/2002/06/index.html) Software Productivity Center Inc. Software Cost Estimation. Cited 20 January 2003. Available from the World Wide Web: (http://spc.ca/resources/metrics/)

Overview: 

Overview Why We Estimate? Why Projects are Poorly Estimated Steps in the Estimation Process Predicting the Size Deliverables Tips on Better Estimation

Introduction: 

Introduction Estimation is important activity in software development and as a whole, the software industry does not estimate projects well. A little focus on this subject would help improve the situation

Why We Estimate?: 

Why We Estimate? To complete projects on time and within budget Under-estimating Under- Staffing resulting in staff burnout Setting too short a schedule results in loss of credibility as deadlines are missed Over-estimating Projects cost more than they should resulting in unnecessary cost Projects take longer to deliver resulting in lost opportunities

Why Software Projects are Poorly Estimated: 

Why Software Projects are Poorly Estimated Lack of Understanding about Estimation What is Estimation? Probability Statements 1 2 3 5 4 6 7 8 9 10 Months 25 95 80 60 0 Probability of Completion Estimated Completion Time Impossible %

Poor Estimation: 

Poor Estimation Lack of Understanding about Estimation What is the difference between target setting and estimation? Estimation Process NOT open to debate Inputs Open to debate Not Open to debate Outputs

Poor Estimation: 

Poor Estimation Not Scheduling Estimation Creating effective and efficient metrics program

Steps in the Estimation Process: 

Steps in the Estimation Process Predict Sizes of the Deliverables Output include specification volumes, source code volumes, user documentation volumes, user documentation volumes, number of test cases, number of possible bugs Selecting Project Activities 25 common activities in software project

Steps in the Estimation Process: 

Steps in the Estimation Process Estimate Staffing Levels High number of different occupation groups makes this step hard Estimating Software Work Effort Amount of human work associated with a project expressed in time Estimating Software Costs Salary and effort used to calculate costs

Steps in the Estimation Process: 

Steps in the Estimation Process Estimating Software Schedules Schedules are missed because of they are overruled by clients or senior executives, creeping requirements, and inadequate quality control Estimating Defect Potentials Project exceed budgets/schedules because too many bugs project cannot be released

Steps in the Estimation Process: 

Steps in the Estimation Process Estimating Defect Removal Efficiency Adjusting Estimates in Response to Technologies Estimating Maintenance Costs over Time

Predicting the Size of Deliverables: 

Predicting the Size of Deliverables Developer Opinion Experienced guess Previous Project Experience Using metrics data Count Function Blocks Relies on systems being decomposed into same number of “levels”

Predicting the Size of Deliverables: 

Predicting the Size of Deliverables Function Point Analysis External Inputs, External Outputs, External Inquiries, External Interfaces, Internal data files Calculate the size of the project Combing Estimates estimate several ways, and then calculate a weighted average of the estimates

Tips for Better Estimation: 

Tips for Better Estimation Find developer skill level of estimating Bentley’s Estimation Quiz Create Feedback Loop Practice Makes Perfect Divide Projects into Small Tasks Give Best/Worst/Most Likely Use Group Estimation Techniques

Rome Built in A Day?: 

Rome Built in A Day? Effective Estimates are developed by process definition and improvement, education and training, good project management, use of proper tools and techniques, measurement, sufficient resources so it could be several years before estimates can actually be made