principles of user-centered design
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Principles of User-Centered Design. CSCI 4800/6800 Feb. 1, 2006. What is design?. Finding the right components of a physical structure A goal-directed problem-solving activity - PowerPoint PPT PresentationTRANSCRIPT
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Principles of User-Centered Design
CSCI 4800/6800
Feb. 1, 2006
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What is design?
Finding the right components of a physical structure A goal-directed problem-solving activity Simulating what we want to make or do before we
make or do it – as many times as may be necessary to feel confident in the final result
Engineering design: “the use of scientific principles, technical information and imagination in the definiton of a mechanical structure, machine or system to perform pre-specified functions with the maximum efficiency and economy.
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Approaches
Formal specifications Custom crafted / creative
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User-Centered Design
Principles– Make user issues central in the design process– Carry out early testing and evaluation with users– Design iteratively
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Methods for UCD
Soft Systems Methodology (SSM) Open Systems Task Analysis (OSTA) Multiview Star Life Cycle
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Soft Systems Methodology
Focuses on planning Approach developed by Checkland, Schloes
’81, ’91 Emphasis : understand the problem and its
situation
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SSM
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Stages in SSM
Stages 1 and 2 – obtain “rich expression” of the problem: meetings with stakeholders
Stage 3 – obtain precise definition of the system
Stage 4 – produce conceptual models: abstract representation, “root definition”
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SSM, “root definition”
• C - Clients (people who will benefit/suffer) • A - Actors (who is involved with system) • T - Transformation (purpose) • W - Weltanschauung/World View
(perspective from which root definition is formulated)
• O - Owners (who has commissioned system) • E - Environment
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SSM
Stage 5 – compare “root definition” of stage 4 with “rich expression” of stage 2; iterate until gaps are filled
Stage 6 – identify changes Stage 7 – recommend an action
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SSM
Benefits for HCI engineering:– Identifies people, constraints, view of system– Develops conceptual models
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Cooperative Design
Participative design – users participate in design process
Sociotechnical design – considers both social and technical alternatives/solutions to/ aspects of problems
OSTA – Open Systems Task Analysis (Eason, Harker ’89)
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OSTA
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OSTA
Specified together:– Technical requirements
System structure, functionality
– Social system requirements Usability, acceptability
Goal:– Provide method for understanding what occurs
when computer system is introduced into a working environment
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OSTA – Systems Analysis (top)
1. Primary task stated (goals of group of workers identified) 2. Task inputs identified - usually come from outside the system - character of inputs
may vary & affect way system behaves 3. External environment - including physical environment, economic, political
conditions, demand for task output 4. Transformation processes described typically - object/action flowchart of objects
to be transformed & actions neccessary to transform them with annotations
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OSTA – technical and social
5. Social system analyzed • Roles of people in relation to one another • Characteristics & qualities of users of new system
6. Technical system analyzed - how will new system be integrated with others systems & what remains of the old system?
7. Performance satisfaction – for social system under new technical systems
8. Requirements for new technical system, based on the task analysis• Functionality, usability, acceptability
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Problems:
Need expert to guide the design process Ability to integrate with other design
processes/methods Need “right” organizational and political climate Cost-effective???
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Multiview
Combines sociotechnical and soft-systems approaches Stage 1: create PTM (primary task model) – similar to
“root def” Stage 2: conceptual modeling of info flows/ structure,
produce FM (functional model), ER model, dataflow models
Stage 3: design people tasks (PT), role sets (RS), and computer task requirements (CTR)
Stage 4: design the HCI Stage 5: technical design
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Multiview
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Multiview
Provides more direction for system designers
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Star Life Cycle
No prescribed ordering of activities Based on actual design practive of HCI
designers Emphasis on prototyping and evaluation Rapid prototyping, incremental development
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The Star Life Cycle
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Star Life Cycle
Conceptual design – what is required? What should system do? What data is required? What will users need to know?
Physical design (formal design) : how to achieve the conceptual design …
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Methods for UCD
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Example: Olympic Messaging Service (1984 Los Angeles Olympic Games)
Kiosks at which athletes could send & receive voice messages among themselves
Or people from around the world could send messages in to athletes & official
Twelve languages (no translation)
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OMS - Process
Paper scenarios of user interface prepared – Comments from designers, management, prospective
users – Some functions altered, others dropped
Brief user guides prepared, tested, developed iteratively (~200 iteratives)
– Simulations constructed & evaluated; help messages designed
– Simulations tested with users
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OMS - Process
Needed to add undo/backup button Visit to village site, demos & interviews with
ex-olympians & others involved Prototype developed & tested
– "Hallway" method to collect info on height & layout of prototype kiosk
– "Try-to-destroy-it" tests of robustness (CS students)
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OMS – summary
Focus on users & tasks early in design process, including user guides, help, & ensuring that user's cognitive, social, & attitudinal characteristics are understood & accomodated
Measure reactions by using prototype manuals, interface, & other simulations of the system
Design iteratively All usability factors must evolve together and be
under the responsibility of one control group
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Example: Air Traffic Control System
Original system – Variety of info needed, each from own source -
some on desk, some on ceiling, some not in line of sight
– Dials – Closed Circuit TV – Temporary instructions
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Air Traffic Control
Desire: Integrated data display system SAFETY (major concern) "Upgradeable" Variety of airports/local requirements Modified info requirements Layouts specific to controller & task More color Ability to add pages for specific local conditions Simple editing facilities for updates
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Example – Air Traffic Control System
Process:– Evaluate controller’s task– Develop first-cut design– Establish user-systems design group– Concept testing, user feedback– Produce upgraded prototype– Road-show to five airports– Develop systems specification– build and install system– establish new needs