Table of Contents
1. Introduction 9
1.1 Why do requirements matter? 9
1.2 Who are requirements for? 12
1.3 Different names for requirements 13
1.4 Different types of specification 14
1.5 The challenge of writing better requirements 15
1.6 The requirements writing process 18
2. Identifying the stakeholders 21
2.1 Different types of stakeholder 21
2.2 Your house extension: a simple case? 22
2.3 A practical approach to identifying stakeholders 23
Exercise 1: Listing the stakeholders 23
3. Gathering requirements from stakeholders 26
3.1 Possible techniques 26
Exercise 2: Asking 'why?' 28
3.2 Interviews 28
3.3 Workshops 32
3.4 Experiencing life as a user 36
3.5 Observing users at work 36
3.6 Acting out what needs to happen 36
3.7 Prototypes 38
4. Other sources of requirements 40
4.1 Possible sources 40
Exercise 3: Extracting requirements from source documents 44
Exercise 4: Extracting requirements from a memo 45
4.2 Getting requirements for mass-market products 45
4.3 User requirements in subsystem projects 46
5. Structuring the requirements 47
5.1 You need structure as well as text 47
5.2 Breaking the problem down into steps 48
5.3 Organizing requirements into scenarios 50
5.4 Examples of goal decomposition 52
Exercise 5: A structure for user requirements 53
5.5 Handling exceptions 53
Exercise 6: Could anything go wrong here? 54
Exercise 7: Exceptions 55
5.6 Examples and exercises in requirement structure 57
Exercise 8: Creating a heading structure 57
Exercise 9: The right document for each subject 57
Exercise 10: Wrongly placed requirements 58
6. Requirements in context 59
6.1 The user requirements document 59
6.2 Organizing the constraints 60
Exercise 11: Writing constraints 64
6.3 Defining the scope 64
Exercise 12: Restricting the scope 65
6.4 Requirement attributes 65
6.5 Keeping track of the requirements 67
7. Requirements writing 70
7.1 Quality, not perfection 70
7.2 Sketch, then improve 70
7.3 Anatomy of a good requirement 70
7.4 Guidelines for good requirements 71
7.5 Don't write like this 72
Exercise 13: Good requirements 75
Exercise 14: Writing requirements for familiar domestic systems 75
Exercise 15: Ambiguous requirements 76
8. Checking and reviewing 78
8.1 Checking the document structure with users 78
8.2 Checking the requirements 80
Exercise 16: Checking individual requirements 81
Exercise 17: Checking a set of requirements 82
8.3 Reviewing 83
8.4 Success - the reviewed document 85
Exercise 18: Reviewing 85
A: Answers to exercises 87
Exercise 1: Listing the stakeholders 87
Exercise 2: Asking 'why?' 87
Exercise 3: Extracting requirements from source documents 87
Exercise 4: Extracting requirements from a memo 88
Exercise 5: A structure for user requirements 88
Exercise 6: Could anything go wrong here? 89
Exercise 7: Exceptions 89
Exercise 8: Creating a heading structure 90
Exercise 9: The right document for each subject 90
Exercise 10: Wrongly placed requirements 90
Exercise 11: Writing constraints 91
Exercise 12: Restricting the scope 92
Exercise 13: Good requirements 92
Exercise 14: Writing requirements for familiar domestic systems 93
Exercise 15: Ambiguous requirements 93
Exercise 16: Checking individual re
