User Centred Design and Pact Analysis
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Transcript of User Centred Design and Pact Analysis
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User Centred Design
Gould and Lewis 1975
Early focus on users and tasks
Empirical measurement
Iterative design
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User Centred Design Principles
Users tasks and goals are driving force behind
development
Users behaviour and context of use are studied and
the system is designed to support them
Users characteristics are captured and designed for
Users are consulted throughout the development and
their input taken into account
All design decisions are taken within the context of
the users, their work and the environment
(Preece et al 2002)
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User needs analysis/PACT
User characterisation orStakeholder
analysis
Primary users
Secondary users
Task analysis/description
Context Analysis
aka Environment Analysis
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Who are the Users ?
People who interact directly with the product to achieve a
task?Primary Users
Those likely to be frequent hands-on user of the system
Secondary Users
Occasional users or those who use the system through anintermediary
Tertiary Users
Those affected by the introduction of the system or who willinfluence its purchase
Facilitating Users
Those who are involved with design, development and maintenanceof the system.
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User Characterisation
user characteristics physical abilities and skills
general abilities
knowledge computer familiarity
naive
novice
skilled
expert
frequency of use casual
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Task description
Who?
What?
Where?
When?
How often?
Task dependencies
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Task analysis
goal, device, tasks, sub-tasks, actions
Edit letter Print letter
Enter text Amend ......
...... ......
Move cursor
TASKSGOAL
Produce a letter
Selecting a device
determines the tasks
DEVICE
(Preece et al, p412)
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Goals, tasks, actions :
terminology
Goal = external task, such as producing a letter
Device = method, tool, or technique appropriate forachieving goals
Tasks = activities necessary to achive goals using adevice
Subtasks = components of tasks
Actions = simple tasks w/ no control structureMethod = plan = number of tasks or actions linked
into a sequence
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Diagrammatic HTA
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Refining the description
Given initial HTA (textual or diagram)
How to check / improve it?
Some heuristics:paired actions e.g., where is `turn on gas'
restructure e.g., generate task `make pot'
balance e.g., is `pour tea' simpler than making pot?
generalise e.g., make one cup .. or more
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Refined HTA for making tea
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Types of plan
fixed sequence - 1.1 then 1.2 then 1.3
optional tasks - if the pot is full 2
wait for events -when kettle boils 1.4
cycles - do 5.1 5.2 while there are still empty cups
time-sharing - do 1; at the same time ...
discretionary - do any of 3.1, 3.2 or 3.3 in any order
mixtures - most plans involve several of the above
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Environment analysis
Physical environment location of activity
physical objects heat, light, noise etc
Social and Organisational context location of people
communication
interruptions
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Technology
New/old computers
Fast/slow network connections
Large/small screens
Desktop/portable/pervasive/wearable
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Interaction Design
Identifying needs and establishing
requirements Developing alternative designs
Building interactive versions of designs
Evaluating designs
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Standards and Guidelines
Principles
strive for consistency
Rules adopt a consistent format for the location of
various display features from one display to
another
House styles
Standards and directives
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Prototyping
Low fidelity
High fidelity
Horizontal
Vertical
Throw away
Evolutionary
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Premises:
The system should be designed to
match user requirements - people
should not have to change to fit in withthe system
People should be able to concentrate
on their activities rather than on how touse the system