Identifying needs and establishing requirements. Overview The importance of requirements Different types of requirements Data gathering Task descriptions:Scenarios.

Identifying needs and establishing

requirements

Overview

•The importance of requirements

•Different types of requirements

•Data gathering

•Task descriptions: Scenarios

Use Cases

Essential use cases

•Task analysis: HTA

What, how and why? •What

Two aims: 1. Understand as much as possible about users, task, context2. Produce a stable set of requirements

•How:Data gathering activitiesData analysis activitiesExpression as ‘requirements’All of this is iterative

What, how and why?

•Why:Requirements definition: the stage where failure occurs most commonlyGetting requirements right is crucial

Different kinds of requirements

• Functional: —What the system should do—Historically the main focus of requirements activities

•(Non-functional: memory size, response time... )• Data:

—What kinds of data need to be stored?—How will they be stored (e.g. database)?

Different kinds of requirements

Environment or context of use:

—physical: dusty? noisy? vibration? light? heat? humidity? …. (e.g. OMS insects, ATM)—social: sharing of files, of displays, in paper, across great distances, work individually, privacy for clients—organisational: hierarchy, IT department’s attitude and remit, user support, communications structure and infrastructure, availability of training

Different kinds of requirements

•Users: Who are they?—Characteristics: ability, background, attitude to computers—System use: novice, expert, casual, frequent—Novice: step-by-step (prompted), constrained, clear information—Expert: flexibility, access/power—Frequent: short cuts—Casual/infrequent: clear instructions, e.g. menu paths

Different kinds of requirements

•Usability: learnability, throughput, flexibility, attitude

Note that user requirements and usability requirements refer to different things

Data gathering techniques (1)Questionnaires:

—A series of questions designed to elicit specific information

—Questions may require different kinds of answers: simple YES/NO; choice of pre-supplied answers; comment

—Often used in conjunction with other techniques

—Can give quantitative or qualitative data—Good for answering specific questions from

a large, dispersed group of people

Data gathering techniques (2)

Interviews:

—Forum for talking to people

—Structured, unstructured or semi-structured

—Props, e.g. sample scenarios of use,

prototypes, can be used in interviews

—Good for exploring issues

—But are time consuming and may be

infeasible to visit everyone

Data gathering techniques (3)

Workshops or focus groups: —Group interviews —Good at gaining a consensus view and/or

highlighting areas of conflict

Data gathering techniques (4)Naturalistic observation:

—Spend time with stakeholders in their day-to-day tasks, observing work as it

happens—Gain insights into stakeholders’ tasks —Good for understanding the nature and

context of the tasks—But, it requires time and commitment

from a member of the design team, and it can result in a huge amount of data

—Ethnography is one form

Data gathering techniques (5)

Studying documentation: —Procedures and rules are often written

down in manuals —Good source of data about the steps

involved in an activity, and any regulations governing a task

—Not to be used in isolation—Good for understanding legislation, and

getting background information—No stakeholder time, which is a limiting

factor on the other techniques

Some basic guidelines

•Focus on identifying the stakeholders’ needs

•Involve all the stakeholder groups

•Involve more than one representative from

each stakeholder group

•Use a combination of data gathering

techniques

Some basic guidelines

•Support the process with props such as prototypes

and task descriptions

•Run a pilot session

•You will need to compromise on the data you collect

and the analysis to be done, but before you can

make sensible compromises, you need to know what

you’d really like

•Consider carefully how to record the data

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

Task descriptions

•Scenariosan informal narrative story, simple, ‘natural’, personal, not generalisable

•Use cases—assume interaction with a system—assume detailed understanding of the interaction

•Essential use cases—abstract away from the details—does not have the same assumptions as use cases

Scenario for shared calendar

“The user types in all the names of the meeting participants together with some constraints such as the length of the

meeting, roughly when the meeting needs to take place, and possibly where it needs to take place. The system then checks

against the individuals’ calendars and the central departmental calendar and presents the user with a series of

dates on which everyone is free all at the same time. Then the meeting could be confirmed and written into people’s

calendars. Some people, though, will want to be asked before the calendar entry is made. Perhaps the system could email them automatically and ask that it be confirmed before it is

written in.”

Use case for shared calendar

1. The user chooses the option to arrange a meeting.2. The system prompts user for the names of attendees.3. The user types in a list of names.4. The system checks that the list is valid.5. The system prompts the user for meeting constraints.6. The user types in meeting constraints.7. The system searches the calendars for a date that satisfies the constraints. 8. The system displays a list of potential dates.9. The user chooses one of the dates.10. The system writes the meeting into the calendar.11. The system emails all the meeting participants informing them of them appointment

Alternative courses for shared calendar

Some alternative courses:

5. If the list of people is invalid,5.1 The system displays an

error message.5.2 The system returns to step

2.8. If no potential dates are found,

8.1 The system displays a suitable message.8.2 The system returns to step 5.

Example use case diagram for shared calendar

Administrator Departmentalmember

Arrange ameeting

Update calendarentry

Retrievecontact details

Example essential use case for shared calendar

arrangeMeetingUSER INTENTION SYSTEM RESPONSIBILITYarrange a meeting

request meeting attendees & constraints

identify meeting attendees & constraints

search calendars for suitable dates

suggest potential dateschoose preferred date

book meeting

Task analysis

• Task descriptions are often used to envision new systems or devices

• Task analysis is used mainly to investigate an existing situation

• It is important not to focus on superficial activitiesWhat are people trying to achieve? Why are they trying to achieve it?How are they going about it?

• Many techniques, the most popular is Hierarchical Task Analysis (HTA)

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

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

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 and workshops, naturalistic observation, studying documentation

• 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

Design, prototyping and construction

Overview

•Prototyping and construction

•Conceptual design

•Physical design

•Tool support

What is a prototype?

In interaction design it can be (among other things):a series of screen sketchesa storyboard, i.e. a cartoon-like series of scenes a Powerpoint slide showa video simulating the use of a systema lump of wood (e.g. PalmPilot)a cardboard mock-upa piece of software with limited functionality written in the target language or in another language

Why prototype?

•Evaluation and feedback are central to interaction design•Stakeholders can see, hold, interact with a prototype more easily than a document or a drawing•Team members can communicate effectively•You can test out ideas for yourself •It encourages reflection: very important aspect of design •Prototypes answer questions, and support designers in choosing between alternatives

What to prototype?

•Technical issues

•Work flow, task design

•Screen layouts and information display

•Difficult, controversial, critical areas

Low-fidelity Prototyping

•Uses a medium which is unlike the final medium, e.g. paper, cardboard

•Is quick, cheap and easily changed

•Examples:sketches of screens, task sequences, etc‘Post-it’ notesstoryboards‘Wizard-of-Oz’

Storyboards

•Often used with scenarios, bringing more detail, and a chance to role play

•It is a series of sketches showing how a user might progress through a task using the device

•Used early in design

Sketching

•Sketching is important to low-fidelity prototyping

•Don’t be inhibited about drawing ability. Practice simple symbols

•Index cards (3 X 5 inches)

•Each card represents one screen

•Often used in website development

Using index cards

‘Wizard-of-Oz’ prototyping•The user thinks they are interacting with a computer, but a developer is responding to output rather than the system. •Usually done early in design to understand users’ expectations•What is ‘wrong’ with this approach?

>Blurb blurb>Do this>Why?

User

High-fidelity prototyping•Uses materials that you would expect to be in the

final product.

•Prototype looks more like the final system than a

low-fidelity version.

•For a high-fidelity software prototype common

environments include Macromedia Director, Visual

Basic, and Smalltalk.

•Danger that users think they have a full

system…….see compromises

Compromises in prototyping

•All prototypes involve compromises•For software-based prototyping maybe there is a slow response? sketchy icons? limited functionality? •Two common types of compromise

• ‘horizontal’: provide a wide range of functions, but with little detail• ‘vertical’: provide a lot of detail for only a few functions

•Compromises in prototypes mustn’t be ignored. Product needs engineering

Construction •Taking the prototypes (or learning from them) and creating a whole

•Quality must be attended to: usability (of course), reliability, robustness, maintainability, integrity, portability, efficiency, etc

•Product must be engineered

Evolutionary prototyping

‘Throw-away’ prototyping

Conceptual design: from requirements to design

•Transform user requirements/needs into a conceptual model •“a description of the proposed system in terms of a set of integrated ideas and concepts about what it should do, behave and look like, that will be understandable by the users in the manner intended” •Don’t move to a solution too quickly. Iterate, iterate, iterate•Consider alternatives: prototyping helps

Three perspectives for a conceptual model

•Which interaction mode?How the user invokes actionsActivity-based: instructing, conversing, manipulating and navigating, exploring and browsing. Object-based: structured around real-world objects

Three perspectives for a conceptual model

•Which interaction paradigm? desktop paradigm, with WIMP interface (windows, icons, menus and pointers),ubiquitous computingpervasive computingwearable computingmobile devices and so on.

•Is there a suitable metaphor?(contd)….

Is there a suitable metaphor?

•Interface metaphors combine familiar knowledge with new knowledge in a way that will help the user understand the product.

•Three steps: understand functionality, identify potential problem areas, generate metaphors

•Evaluate metaphors:How much structure does it provide?How much is relevant to the problem?Is it easy to represent?Will the audience understand it?How extensible is it?

Expanding the conceptual model

•What functions will the product perform? What will the product do and what will the human do (task allocation)?

•How are the functions related to each other? sequential or parallel?categorisations, e.g. all actions related to telephone memory storage

•What information needs to be available?What data is required to perform the task? How is this data to be transformed by the system?

Using scenarios in conceptual design

•Express proposed or imagined situations •Used throughout design in various ways

scripts for user evaluation of prototypesconcrete examples of tasksas a means of co-operation across professional boundaries

•Plus and minus scenarios to explore extreme cases

Using prototypes in conceptual design

•Allow evaluation of emerging ideas

•Low-fidelity prototypes used early on, high-fidelity prototypes used later

Physical design: getting concrete

•Considers more concrete, detailed issues of designing the interface•Iteration between physical and conceptual design•Guidelines for physical design

Nielsen’s heuristicsShneiderman’s eight golden rulesStyles guides: commercial, corporate

decide ‘look and feel’ for youwidgets prescribed, e.g. icons, toolbar

Physical design: getting concrete

•Different kinds of widget (dialog boxes, toolbars, icons, menus etc)

menu designicon designscreen designinformation display

Menu design

•How long is the menu to be?

•In what order will the items appear?

•How is the menu to be structured, e.g. when to use sub-menus, dialog boxes?

•What categories will be used to group menu items?

Menu design

•How will division into groups be denoted, e.g. different colors, dividing lines?

•How many menus will there be?

•What terminology to use? (results of requirements activities will indicate this)

•How will any physical constraints be accommodated, e.g. mobile phone?

Icon design

•Good icon design is difficult•Meaning of icons is cultural and context sensitive•Some tips:

always draw on existing traditions or standardsconcrete objects or things are easier to represent than actions

•From clip art, what do these mean to you?

Screen designTwo aspects:

•How to split across screens moving around within and between screenshow much interaction per screen?serial or workbench style?

•Individual screen designwhite space: balance between enough information/interaction and claritygrouping items together: separation with boxes? lines? colors?

Screen design: splitting functions across screens

•Task analysis as a starting point

•Each screen contains a single simple step?

•Frustration if too many simple screens

•Keep information available: multiple screens open at once

Screen design: individual screen design

•Draw user attention to salient point, e.g. colour, motion, boxing•Animation is very powerful but can be distracting•Good organization helps: grouping, physical proximity•Trade off between sparse population and overcrowding

Information display

•Relevant information available at all times

•Different types of information imply different kinds of display

•Consistency between paper display and screen data entry

Summary•Different kinds of prototyping are used for different purposes and at different stages

•Prototypes answer questions, so prototype appropriately

•Construction: the final product must be engineered appropriately

•Conceptual design (the first step of design)

•Physical design: e.g. menus, icons, screen design, information display

•Prototypes and scenarios are used throughout design