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CMC/CC A Usability Evaluation. Master IK, CIW, MMI L.M. Bosveld-de Smet Course 4; mon. 02/10/06; 16.00-18.00. Usability Evaluation. Design of interaction Dix et al. (2004). What is wanted. Analysis. Design. Usability Evaluation. Implement and deploy. Prototype.

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cmc cc a usability evaluation

CMC/CC AUsability Evaluation

Master IK, CIW, MMI

L.M. Bosveld-de Smet

Course 4; mon. 02/10/06; 16.00-18.00

design of interaction dix et al 2004
Design of interactionDix et al. (2004)

What is

wanted

Analysis

Design

Usability

Evaluation

Implement

and deploy

Prototype

design process of usable interactive systems
Design process of usable interactive systems
  • Interaction design process
    • Complex
    • Iterative
    • Never complete
  • User-centered design
    • Within software engineering framework
  • Design rules
  • Implementation support
  • Evaluation techniques
  • Universally accessible designs
  • Provision of user support
3 related concepts
3 related concepts
  • Usability: measure of success of a product
  • User-Centered Design: design involving user participation
  • Usability Engineering:
    • Whole process ensuring usable interactive systems
    • Process aiming at systems fit for the user, the task, the environment
    • Process implying user participation during software development
    • Process committing itself to design-evaluate-redesign development cycle
    • In search for objective measures for user interface
usability different views
Usability: different views
  • Same intuitions vs. Different approaches
  • Different views on:
    • Definition of usability
      • Usability attributes
    • Importance of user-centered design
    • When and how to deal with user participation
    • How to build usable systems
    • How to measure usability
usability attributes shackel s view
Usability Attributes: Shackel’s view
  • “A usable product is one that users find satisfactory for the tasks for which it was designed.”
  • “Good design for usability depends upon achieving successful harmony in the dynamic interplay between user, task, system, and environment.”
  • Usability: 4 usable criteria
    • Learnability
    • Effectiveness
    • Attitude
    • Flexibility
usability attributes iso definition
Usability Attributes: ISO definition
  • “Usability is the effectiveness, efficiency and satisfaction with which specified users can achieve specified goals in particular environments.”
    • Effectiveness: “accuracy and completeness with which users achieve specific goals”
    • Efficiency: “accuracy and completeness of goals in relation to resources expended”
    • Satisfaction: “comfort and acceptability of the system”
an aside user interface standards
An aside: User Interface Standards
  • Disadvantages:
    • Constrain design
    • Stagnate innovation
    • Describe principles, do not provide solutions
    • Become quickly obsolete
  • Advantages:
    • Define ‘good practice’
    • Affect attitudes w.r.t. ‘software development’
user centered design karat s view
User-Centered Design: Karat’s view
  • Karat (1996) “UCD: Quality or Quackery?”
  • “UCD is an iterative process whose goal is the development of usable systems, achieved through involvement of potential users of a system in system design”
  • “I suggest we consider UCD a nice fluffy little catch phrase. It captures a commitment that the usability community supports – that you must involve users in system design – while leaving fairly open how this is accomplished”
ucd a more objective view
UCD: a more objective view
  • UCD can be accomplished through the application of Usability Engineering
  • Design should centre on users
  • End-user should be consulted
  • Needs of end-users should be considered
hci in software process
HCI in software process
  • Software engineering
  • Usability engineering
  • Iterative design practices
  • Design rationale
waterfall model
Waterfall model

Requirements

Specification

Architectural

design

Detailed

Design

Implementation

and Unit testing

Integration and

Testing

Operation and

Maintenance

usability engineering
Usability Engineering
  • Usability specification as part of requirements specification
  • Iteration and testing
  • List of usability measurement requirements

(Whiteside, Bennett and Holtzblatt, 1988)

    • Time to complete a task
    • Ratio of successes to failures
    • Time spent in errors
    • Number of commands used
    • Frequency of help and documentation use
iteration in waterfall model
Iteration in waterfall model

Requirements

Specification

Architectural

design

Detailed

Design

Implementation

and Unit testing

Integration and

Testing

Operation and

Maintenance

usability engineering lifecycle faulkner 2000
Usability Engineering LifecycleFaulkner (2000)
  • Know the user
  • Know the task
  • User requirements capture
  • Setting usability goals
  • Design process
  • Apply guidelines, heuristics
  • Prototyping
  • Evaluation with users
  • Redesign and evaluation with users
  • Evaluation with users and report
role of prototyping
Role of prototyping

Design

OK?

Prototype

Evaluate

Done!

Not OK?

Redesign

iterative design and prototyping
Iterative design and prototyping
  • Three main approaches to prototyping
    • Throw-away prototyping within requirements specification
    • Incremental prototyping within the life cycle
    • Evolutionary prototyping throughout the life cycle
throw away prototyping
Throw-away prototyping

Preliminary

Requirements

Build

Prototype

Evaluate

Prototype

Adequate?

no

Final

Requirements

yes

evolutionary prototyping
Evolutionary prototyping

Req

Build Prototype

Arch

Det

Evaluate

Prototype

Impl

Int

Operation and

Maintenance

usability evaluation ue
Usability Evaluation (UE)
  • Methodologies for measuring usability aspects of system’s user interface and identifying specific problems (Dix et al. 1998; Nielsen 1993)
  • Should occur throughout design life cycle
  • Common activities:
    • Capture
    • Analysis
    • Critic
  • There is a wide range of UE techniques
  • Each technique has its own requirements
  • Different techniques uncover different usability problems
taxonomies of ue 1
Taxonomies of UE (1)
  • Formative vs. Summative
  • Analytical vs. Empirical
  • Expert analysis vs. User participation
    • Analytic methods
    • Review methods
    • Model-based methods

vs.

    • Experimental methods
    • Observational methods
    • Query methods
taxonomies of ue 2
Taxonomies of UE (2)
  • Automated vs. Non-automated
  • Ivory and Hearst (2001):
    • Testing
    • Inspection
    • Inquiry
    • Analytical modeling
    • Simulation
important factors choice ue
Important factors choice UE
  • Stage in cycle at which UE is carried out
  • Style of UE
  • Level of subjectivity or objectivity of UE technique
  • Type of measures provided
  • Information provided
  • Immediacy of response
  • Level of interference implied
  • Resources required
vocabulary application
Vocabulary application
  • Task analysis
  • Feasability study
  • Design representation
feasibility study
Feasibility study
  • Why is system needed?
  • How will system help to improve user task performance?
  • Are there critical processes that need to be supported by system?
  • What are the technical implications?
  • Can system be produced within given budget?
  • Is there a timescale for the development of the system?
strategies for representing design
Strategies for representing design
  • Storyboards
  • State transition diagrams
  • Simulations
  • Scenarios
  • Rapid prototyping
  • Wizard of Oz
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