1. Week 8 - The process of interaction design
Prof. Ahmed Sameh

2. Overview What is involved in Interaction Design? Some practical issues
Importance of involving users
Degrees of user involvement
What is a user-centered approach?
Four basic activities
Some practical issues
Who are the users?
What are ‘needs’?
Where do alternatives come from?
How do you choose among alternatives?
A simple lifecycle model for Interaction Design
Lifecycle models from software engineering
Lifecycle models from HCI

3. What is involved in Interaction Design?
It is a process:
a goal-directed problem solving activity informed by intended use, target domain, materials, cost, and feasibility
a creative activity
a decision-making activity to balance trade-offs
It is a representation:
a plan for development
a set of alternatives and successive elaborations

4. Importance of involving users
Expectation management
Realistic expectations
No surprises, no disappointments
Timely training
Communication, but no hype
Ownership
Make the users active stakeholders
More likely to forgive or accept problems
Can make a big difference to acceptance and success of product

5. Degrees of user involvement
Member of the design team
Full time: constant input, but lose touch with users
Part time: patchy input, and very stressful
Short term: inconsistent across project life
Long term: consistent, but lose touch with users
Newsletters and other dissemination devices
Reach wider selection of users
Need communication both ways
Combination of these approaches

6. What is a user-centered approach?
User-centered approach is based on:
Early focus on users and tasks: directly studying cognitive, behavioral, anthropomorphic & attitudinal characteristics
Empirical measurement: users’ reactions and performance to scenarios, manuals, simulations & prototypes are observed, recorded and analysed
Iterative design: when problems are found in user testing, fix them and carry out more tests

7. Four basic activities
There are four basic activities in Interaction Design:
1. Identifying needs and establishing requirements
2. Developing alternative designs
3. Building interactive versions of the designs
4. Evaluating designs

8. Some practical issues Who are the users? What are ‘needs’?
Where do alternatives come from?
How do you choose among alternatives?

9. Who are the users/stakeholders?
Not as obvious as you think:
those who interact directly with the product
those who manage direct users
those who receive output from the product
those who make the purchasing decision
those who use competitor’s products
Three categories of user (Eason, 1987):
primary: frequent hands-on
secondary: occasional or via someone else
tertiary: affected by its introduction, or will influence its purchase

10. Who are the stakeholders?

11. What are the users’ capabilities?
Humans vary in many dimensions:
size of hands may affect the size and positioning of input buttons
motor abilities may affect the suitability of certain input and output devices
height if designing a physical kiosk
strength - a child’s toy requires little strength to operate, but greater strength to change batteries
disabilities(e.g. sight, hearing, dexterity)

12. What are ‘needs’? Users rarely know what is possible
Users can’t tell you what they ‘need’ to help them achieve their goals
Instead, look at existing tasks:
their context
what information do they require?
who collaborates to achieve the task?
why is the task achieved the way it is?
Envisioned tasks:
can be rooted in existing behaviour
can be described as future scenarios

13. What do we need to look out for in interface design issues?

15. Where do alternatives come from?
Humans stick to what they know works
But considering alternatives is important to ‘break out of the box’
Designers are trained to consider alternatives, software people generally are not
How do you generate alternatives?
‘Flair and creativity’: research and synthesis
Seek inspiration: look at similar products or look at very different products

16. How do you choose among alternatives?
Evaluation with users or with peers, e.g. prototypes
Technical feasibility: some not possible
Quality thresholds: Usability goals lead to usability criteria set early on and check regularly
safety: how safe?
utility: which functions are superfluous?
effectiveness: appropriate support? task coverage, information available
efficiency: performance measurements

17. Testing prototypes to choose among alternatives

18. HCI in the software process
Software engineering and the design process for interactive systems
Usability engineering
Iterative design and prototyping
Design rationale

19. Lifecycle models Show how activities are related to each other
Lifecycle models are:
management tools
simplified versions of reality
Many lifecycle models exist, for example:
from software engineering: waterfall, spiral, JAD/RAD, Microsoft, agile
from HCI: Star, usability engineering

20. The waterfall model Requirements specification Architectural design
Detailed design
Coding and unit testing
Integration and testing
Operation and maintenance

21. Activities in the life cycle
Requirements specification
designer and customer try capture what the system is expected to provide can be expressed in natural language or more precise languages, such as a task analysis would provide
Architectural design
high-level description of how the system will provide the services required factor system into major components of the system and how they are interrelated needs to satisfy both functional and nonfunctional requirements
Detailed design
refinement of architectural components and interrelations to identify modules to be implemented separately the refinement is governed by the nonfunctional requirements

22. DSDM lifecycle model

23. The Star lifecycle model
Suggested by Hartson and Hix (1989)
Important features:
Evaluation at the center of activities
No particular ordering of activities; development may start in any one
Derived from empirical studies of interface designers

24. The Star Model (Hartson and Hix, 1989)
UCD is a very general philosphy that instantiates itself in the context of a design project. Within HCI there have been many attempts to come up with actual life cycles where users are central. Examples include Rubinstein and Hersch successive iteration of 5 stages, info collecion, design, implementation, evaluation and deploment. The one here is taken fromHartson and Hix
model came about by analysing how design takes place in practice
evaluation is central: results of each ativity are evaluated before going onto next one
both bottom-up and top -down required in waves
software designers are familiar with this in their work and call it ‘yo-yoing’
it is important to do both structure and detail at the same time
in practice this is what is done - but the end result suggests otherwise corporate requirments dictate a top=down approach which is wha gets recorded
ch 5 of Developing User Interfaces (An Overview of Systems Analysis and Design) p- nice step-by-step methodology for doing user-centred design

25. Usability engineering lifecycle model
Reported by Deborah Mayhew
Important features:
Holistic view of usability engineering
Provides links to software engineering approaches, e.g. OOSE
Stages of identifying requirements, designing, evaluating, prototyping
Can be scaled down for small projects
Uses a style guide to capture a set of usability goals

26. ISO 13407

27. Verification and validation
Real-world requirements and constraints
The formality gap
Verification
designing the product right
 Validation
designing the right product
The formality gap
validation will always rely to some extent on subjective means of proof
Management and contractual issues
design in commercial and legal contexts

28. The life cycle for interactive systems
cannot assume a linear sequence of activities as in the waterfall model
lots of feedback!
Requirements specification
Architectural design
Detailed design
Coding and unit testing
Integration and testing
Operation and maintenance

29. Usability engineering
The ultimate test of usability based on measurement of user experience
Usability engineering demands that specific usability measures be made explicit as requirements
Usability specification
usability attribute/principle
measuring concept
measuring method
now level/ worst case/ planned level/ best case
Problems
usability specification requires level of detail that may not be
possible early in design satisfying a usability specification
does not necessarily satisfy usability

30. part of a usability specification for a VCR
Attribute: Backward recoverability
Measuring concept: Undo an erroneous programming sequence
Measuring method: Number of explicit user actions to undo current program
Now level: No current product allows such an undo
Worst case: As many actions as it takes to program-in mistake
Planned level: A maximum of two explicit user actions
Best case: One explicit cancel action

31. ISO usability standard 9241
adopts traditional usability categories:
effectiveness
can you achieve what you want to?
efficiency
can you do it without wasting effort?
satisfaction
do you enjoy the process?

32. some metrics from ISO 9241
Usability Effectiveness Efficiency Satisfaction objective measures measures measures
Suitability Percentage of Time to Rating scale for the task goals achieved complete a task for satisfaction
Appropriate for Number of power Relative efficiency Rating scale for trained users features used compared with satisfaction with an expert user power features
Learnability Percentage of Time to learn Rating scale for functions learned criterion ease of learning
Error tolerance Percentage of Time spent on Rating scale for errors corrected correcting errors error handling successfully

33. Iterative design and prototyping
Iterative design overcomes inherent problems of incomplete requirements
Prototypes
simulate or animate some features of intended system
different types of prototypes
throw-away
incremental
evolutionary
Management issues
time
planning
non-functional features
contracts

34. Techniques for prototyping
Storyboards
need not be computer-based
can be animated
Limited functionality simulations
some part of system functionality provided by designers
tools like HyperCard are common for these
Wizard of Oz technique
Warning about iterative design
design inertia – early bad decisions stay bad
diagnosing real usability problems in prototypes….
…. and not just the symptoms

35. Design rationale
Design rationale is information that explains why a computer system is the way it is.
Benefits of design rationale
communication throughout life cycle
reuse of design knowledge across products
enforces design discipline
presents arguments for design trade-offs
organizes potentially large design space
capturing contextual information

36. Design rationale (cont’d)
Types of DR:
Process-oriented
preserves order of deliberation and decision-making
Structure-oriented
emphasizes post hoc structuring of considered design alternatives
Two examples:
Issue-based information system (IBIS)
Design space analysis

37. Issue-based information system (IBIS)
basis for much of design rationale research
process-oriented
main elements:
issues
– hierarchical structure with one ‘root’ issue
positions
– potential resolutions of an issue
arguments
– modify the relationship between positions and issues
gIBIS is a graphical version

38. structure of gIBIS Sub-issue Issue Position Argument supports
responds to
objects to
supports
questions
generalizes
specializes

39. Design space analysis structure-oriented QOC – hierarchical structure:
questions (and sub-questions)
– represent major issues of a design
options
– provide alternative solutions to the question
criteria
– the means to assess the options in order to make a choice
DRL – similar to QOC with a larger language and more formal semantics

40. the QOC notation Criterion Option Question Option Criterion Option…
Consequent Question …
Question

41. Psychological design rationale
to support task-artefact cycle in which user tasks are affected by the systems they use
aims to make explicit consequences of design for users
designers identify tasks system will support
scenarios are suggested to test task
users are observed on system
psychological claims of system made explicit
negative aspects of design can be used to improve next iteration of design

42. A simple interaction design model
Exemplifies a user-centered design approach

43. Summary Four basic activities in the design process
Identify needs and establish requirements
Design potential solutions ((re)-design)
Choose between alternatives (evaluate)
Build the artefact
User-centered design rests on three principles
Early focus on users and tasks
Empirical measurement using quantifiable & measurable usability criteria
Iterative design
Lifecycle models show how these are related

44. Summary The software engineering life cycle Usability engineering
distinct activities and the consequences for interactive system design
Usability engineering
making usability measurements explicit as requirements
Iterative design and prototyping
limited functionality simulations and animations
Design rationale
recording design knowledge
process vs. structure