1. Software Requirements and Design Khalid Ishaq

2. Overview The requirements Problem Requirements Management
Analyzing Problems
Understanding the Users Needs
Defining and Refining the System
Managing Scope 2

3. The Requirements Problem
“The goal of software development is to develop quality software – on time and on budget – that meets customers’ real needs.” To obtain this goal we must know:
“Exactly what is the software supposed to do?”
“How do we know that the software is doing exactly that and nothing else?” 3

4. Root Causes of Project Failure
Requirement errors are the most common type of systems development error and the most costly to fix. 4

5. Root Causes of Project Failure
Data (Standish Group 1994 )
$250 Billion each year on 175,000 IT projects.
Average Cost:
Large Projects: $2,322,000
Medium: $1,331,000
Small: $434,000
31% will be cancelled before they are completed or loss of $81 Billion
52.7% will cost 189% of the original estimate or loss of $59 Billion 4

6. Root Causes of Project Failure
Requirements Related
Lack of user input: 13% of all projects
Incomplete requirements and specifications 12% of projects
Changing requirements and specifications 12% 4

7. Root Causes of Project Failure
Non-Requirements Related
Unrealistic schedules 4%
Inadequate staffing 6%
Inadequate technology skills 7% 4

8. Root Causes of Project Failure
Source: European Software Process Improvement Training Initiative (ESPITI) 3800 responses
2 largest Problems in ½ the responses
Req. specifications
Managing customer requirements 4

9. Root Causes of Project Failure
1/3 of projects fail due to requirements gathering, requirements documentation, or requirements management problems 4

10. Root Causes of Project Success
Large companies 9% delivered on time and budget and for small 16% 4

11. Root Causes of Project Success
User involvement 16%
Exec management support 14%
Clear statement of requirements 12% 4

12. Costs Relative Cost to Repair Requirements time 0.1 – 0.2 Design 0.5
Coding 1
Unit Test 2
Acceptance Test 5
Maintenance 20 4

13. Costs
Error that occurred when the development staff created the technical design from a correct set of requirements 7

14. Costs
Error that leaked into the design phase due to wrong requirements.
By the time the req. error is detected, design group has invested time and effort in a design
Assumes the error is design related and takes a while to point to the wrong requirements.
As a result the design will probably be thrown away
Wait a minute! This isn’t a design mistake after all, we’ve got the wrong requirements. 7

15. Requirements Management
What is a Requirement
A requirement is a capability that the system must deliver 8

16. Requirements Management
What is a Requirement Management
Requirements Management is a process of systematically eliciting, organizing and documenting requirements for a complex system. 8

17. Requirements Management
The skill to elicit useful and complete requirements from the users
Since 100’s or 1000’s of req. may be associated with a system, organize them
Documentation of the req. for effective communication among stakeholders 8

18. Eliciting Requirements
Is this a nice-to-have or a must have?
Need or requirement
Statement of the problem or statement of the solution
Goal of the system or a contractual requirement 8

19. Skills Analysis the problem Understand the user needs
Defining the system
Managing scope
Refining the system
Building the right system 8

20. Problem Analysis Gain agreement on the problem definition
Understand the root causes – the problem behind the problem
Identify the stakeholders
Defining the solution system boundary
Identify Constraints 8

21. The Problem Statement The problem of Describe the problem
Effects Identify the stake holders affected by the problem
The result of which Describe the impact of this problem on the stakeholders and business activity
Benefits of indicated the proposed solutions and list a few key benefits. 8

22. Root Causes
Fishbone diagram
Standard Document 8

23. Stakeholders Users of the system Customer (Buyer) of the system
Effected by the output of the system
Executives
Misc. Users
Maintainers
Unknown 8

24. Solution Boundary
Our System
Outside interaction 8

25. Constraints Economics Political Technical System Environment
Schedule and Resources 8

26. END 33