Chapter 10 Identifying needs and establishing requirements

Chapter 10

Identifying needs and establishing requirements

Outline

What, How, and Why? What are requirements? Data gathering for requirements Data analysis, interpretation, and

presentation Task description Task analysis

What, how, and why

What are we trying to achieve in the requirements activity?

Two aims 1) to identify needs -> to understand as much as

possible about the users, their work, and the context of that work

2) to establish requirements -> to produce a set of stable requirements that form a sound basis to move forward into thinking about design

How can we achieve this?

The process seems sequential

1) Gather some data

2) Analyze and interpret the data

3) Extract some requirements from the data

But, actually, the activities influence one another as the process iterates

Why bother? The importance of getting it right

Many research works have reported the significant cost of fixing errors late in the software development lifecycle rather than early, during the requirements activity

What are requirements?

Requirement

A requirement is a statement about an intended product that satisfies what it should do or how it should perform

One of the aims of the requirements activity is to make the requirements as specific, unambiguous, and clear as possible, and that how to tell when they have been fulfilled

Different kinds of requirements

Functional requirements Data requirements Environmental requirements User characteristics Usability goals and user experience goals

Functional requirements

Capture what the product should do

Example: a robot working in a car assembly plant Functional requirement: the robot should be able

to accurately place and weld together the correct pieces of metal

Data requirements

Capture the type, volatility, size/amount, persistence, accuracy, and value of the required data

Example: in the personal banking domain Data must be accurate, must persist over many

months and probably years, is very valuable, and there is likely to be a lot of it

Environmental requirements

Context of use – circumstances in which the interactive products will be expected to operate

Physical environment Social environment Organizational environment Technical environment

Physical environment

Amount of light, noise, dust expected in the operational environment

Will users need to wear protective clothing, such as large gloves or headgear, that might affect the choice of interface type?

How crowded is the environment? e.g. speech interface may not be appropriate to be used in a public space

Social environment

Will data need to be shared? Synchronous vs. asynchronous

Do collaborators have to communicate across great distances?

Organizational environment

How good is user support likely to be? How easily can it be obtained? Are there facilities or resources for training? How efficient or stable is the communications

infrastructure? How hierarchical is the management?

Technical environment

What technologies will the product run on or need to be compatible with?

What technological limitations might be relevant?

Underwater PCs

User characteristics

User’ s abilities User’ s skills Novice, Expert, Casual or Frequent user User’s nationality Educational background Preferences Personal circumstances Physical or mental disabilities

User characteristics

User profile: a collection of attributes for a ‘typical user’

Personas: rich descriptions of typical users of the product synthesized from a number of real users each persona has a unique set of goals include a description of the pretend user’s skills, attitudes,

tasks, and environment a name, a photograph, some personal details user experience goals

Data gathering for requirements

Data gathering

Interviews explore issues involve users

Focus group gain a consensus view highlight areas of conflicts and disagreement help stakeholders to meet designers and each

other

Data gathering

Questionnaires get initial responses to choose people to interview get a wider perspective on particular issues

Direct observation understand the nature of the tasks and the context in which

they are performed

Indirect observation Use less often in requirements activity Good for logging current tasks

Data gathering

Studying documentation good source of data about the steps involved in

an activity, and any regulations governing a task good for understanding legislation and getting

some background information on the work doesn’t involve stakeholder time

Researching similar products

Data gathering

Contextual inquiry Follows an apprenticeship model (user is expert,

designer is apprentice) A combination of observation, discussion, and

reconstruction of past events Four main principles

Context (going to the workplace and seeing what happens)

Partnership (user and developer collaborate) Interpretation (between the user and the developer) Focus (on the goals)

Problems with data gathering (1)

Identifying and involving stakeholders:users, managers, developers, customer reps?, union reps?, shareholders?

Involving stakeholders: workshops, interviews, workplace studies, co-opt stakeholders onto the development team

‘Real’ users, not managers:traditionally a problem in software engineering, but better now

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Problems with data gathering (2)

Requirements management: version control, ownership Communication between parties:

— within development team— with customer/user— between users… different parts of an organisation

use different terminology Domain knowledge distributed and implicit:

— difficult to dig up and understand— knowledge articulation: how do you walk?

Availability of key people

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Problems with data gathering (3)

• Political problems within the organisation

• Dominance of certain stakeholders

• Economic and business environment changes

• Balancing functional and usability demands

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Data gathering guidelines for requirements

Focus on identifying the stakeholders’ needs Involve all the stakeholder groups Involve more than one representative from

each stakeholder group Support the data gathering sessions with

suitable props, e.g. task descriptions and prototypes

Data interpretation and analysis

• Start soon after data gathering session

• Initial interpretation before deeper analysis

• Different approaches emphasize different elements e.g. class diagrams for object-oriented systems, entity-relationship diagrams for data intensive systems

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Brainstorming for innovation

Include participants from a wide range of disciplines, with a broad range of experience

Don’t ban ‘silly stuff’ Use catalysts for further inspiration

Build one idea on top of another Jump back to an earlier idea Consider alternative interpretations

Brainstorming for innovation

Keep records Start the brainstorm with a well-honed

problem Use warm-up exercises, e.g. word games,

exploration of physical items related or unrelated to the problem

Task description

Task description

Scenarios Use cases Essential use cases

Scenarios

Informal narrative description Describes human activities or tasks in a story

that allows exploration and discussion of contexts, needs, and requirements

Does not describe the use of software or other technological support to achieve a task

Use user’s vocabulary and phrasing

Scenarios

Help to understand what people do now So, help to explore constraints, contexts,

irritations, facilitators, etc. Help to identify stakeholders and products

involved in the activity It is a good idea to emphasize the context,

the usability and user experience goals, and the tasks the user is performing

Scenarios

Inclusion of emotional elements helps to increase developers’ understanding of context

Often, they are generated during workshop, interview, or brainstorming sessions to help explain or discuss users’ goals

Can be used to imagine potential uses of a product and to capture existing behavior

Scenarios

Not intended to capture a full set of requirements

Are very personalized account, offering only one perspective

Scenario for holiday planner

“The Thomson family enjoy outdoor activity holidays and want to try their hand at sailing this year. There are four members of the family: Sky who is 10 years old, Eamonn who is 15 years old, Claire who is 35, and Will who is 40. While out on a shopping trip they call by at the travel agents

in their local town to start exploring the possibilities ... The travel organizer is located in a quiet corner of the agents’ office, where there

are comfortable seats and play things for young children. They all gather around the organizer and enter their initial set of requirements—a sailing holiday for four novices. The stand-alone console is designed so that all members of the family can interact easily and comfortably with it. The

system’s initial suggestion is that they should consider a flotilla holiday, where several novice crews go sailing together and provide mutual

support for first-time sailors…”

Use cases

Focus on user goals, but the emphasis here is on a user-system interaction rather than the user’s task itself

Describes ‘normal course’, i.e., the set of actions that the analyst believes to be most commonly performed

Alternative courses are listed at the bottom of the use case

Use cases

More formal than scenarios

More useful at conceptual design stage than during requirements or data gathering

But use cases have been found to help some stakeholders express their views on how existing systems are used and how a new system might work

Use cases

To develop a use case, identify actors (people or system) actors’ goals or goals in using the system

Use case for holiday planner1. The system displays options for investigating visa and vaccination

requirements.

2. The user chooses the option to find out about visa requirements.

3. The system prompts user for the name of the destination country.

4. The user enters the country’s name.

5. The system checks that the country is valid.

6. The system prompts the user for her nationality.

7. The user enters her nationality.

8. The system checks the visa requirements of the entered country for a

passport holder of her nationality.

9. The system displays the visa requirements.

10. The system displays the option to print out the visa requirements.

11. The user chooses to print the requirements.

Alternative courses for

holiday planner Some alternative courses:

6. If the country name is invalid:6.1 The system displays an error message.6.2 The system returns to step 3.

8. If the nationality is invalid:8.1 The system displays an error message.8.2 The system returns to step 6.

9. If no information about visa requirements is found:9.1 The system displays a suitable message.9.2 The system returns to step 1.

Example use case diagram for holiday planner

HolidaymakerTravel agent

Update holiday details

Identify potential Holiday options

Retrieve visa requirements

Retrieve vaccination requirements

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Essential use cases

Represent abstractions from scenarios, i.e. they represent a more general case than a scenario embodies

Try to avoid the assumptions of a traditional use case, i.e. there is a piece of technology to interact with, and assumptions about the user interface and the kind of interaction to be designed

Essential use cases

Is a structured narrative consisting of three parts A name that expresses the overall user intention A stepped description of user actions A stepped description of system responsibility

Instead of actors, essential use cases are associated with user roles

Example essential use case for holiday planner

retrieveVisa

USER INTENTION SYSTEM RESPONSIBILITYfind visa requirements

request destination and nationality

supply required informationobtain appropriate visa info

obtain copy of visa infooffer info in different formats

choose suitable formatprovide info in chosen format

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Task analysis

Task analysis

Used mainly to investigate an existing situation, not to envision new products

What are they trying to achieve, why are they trying to achieve it, and how are they going about it?

Examples: Hierarchical Task Analysis (HTA) Goals, Operations, Methods, and Selection rules

(GOMS)

Hierarchical task analysis Involves breaking a task down into subtasks, then

sub-sub-tasks and so on. These are grouped as plans which specify how the tasks might be performed in practice

HTA focuses on physical and observable actions, and includes looking at actions not related to software or an interaction device

Start with a user goal which is examined and the main tasks for achieving it are identified

Tasks are sub-divided into sub-tasks

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Example Hierarchical Task Analysis

0. In order to borrow a book from the library 1. go to the library 2. find the required book

2.1 access library catalogue2.2 access the search screen2.3 enter search criteria2.4 identify required book 2.5 note location

3. go to correct shelf and retrieve book4. take book to checkout counter

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Example Hierarchical Task Analysis (plans)

plan 0: do 1-3-4. If book isn’t on the shelf expected, do 2-3-4.plan 2: do 2.1-2.4-2.5. If book not identified do 2.2-2.3-2.4.

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Example Hierarchical Task Analysis (graphical)

Borrow a book from the library

go to the library

find required book

retrieve book from shelf

take book to counter

321 4

0

access catalog

access search screen

enter search criteria

identify required book

note location

plan 0: do 1-3-4. If book isn’t on the shelf expected, do 2-3-4.

plan 2: do 2.1-2.4-2.5.If book not identified from information available, do 2.2-2.3-2.4-2.5

2.1 2.2 2.3 2.4 2.5

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Summary• Getting requirements right is crucial

• There are different kinds of requirement, each is significant for interaction design

• The most commonly-used techniques for data gathering are: questionnaires, interviews, focus groups, direct observation, studying documentation and researching similar products

• Scenarios, use cases and essential use cases can be used to articulate existing and envisioned work practices.

• Task analysis techniques such as HTA help to investigate existing systems and practices

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