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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 Presentation
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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 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.
Approaches
Formal specifications Custom crafted / creative
User-Centered Design
Principles– Make user issues central in the design process– Carry out early testing and evaluation with users– Design iteratively
Methods for UCD
Soft Systems Methodology (SSM) Open Systems Task Analysis (OSTA) Multiview Star Life Cycle
Soft Systems Methodology
Focuses on planning Approach developed by Checkland, Schloes
’81, ’91 Emphasis : understand the problem and its
situation
SSM
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”
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
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
SSM
Benefits for HCI engineering:– Identifies people, constraints, view of system– Develops conceptual models
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)
OSTA
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
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
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
Problems:
Need expert to guide the design process Ability to integrate with other design
processes/methods Need “right” organizational and political climate Cost-effective???
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
Multiview
Multiview
Provides more direction for system designers
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
The Star Life Cycle
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 …
Methods for UCD
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)
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
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)
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
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
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
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