models of the user in desing
TRANSCRIPT
Models of the User in DesingModels of the User in Models of the User in DesingDesing
KrisanaKrisana ChinnasarnChinnasarn, Ph.D., Ph.D.August 2005.August 2005.
Dept. of Computer Science, Burapha University.
Topics• User requirement modelling
– Socio-technique models– Soft system methodology– Participatory design
• Cognitive models– Hierarchical model– Linguistic model– Cognitive architectures
User requirement modellingUser requirement User requirement modellingmodelling
Dept. of Computer Science, Burapha University.
User requirement modelling• User requirement focuses primarily on the
functional requirements of the system –what the system must be able to do- with less emphasis on non-functional human issue such as usability and acceptability.
• User requirement modelling redresses this balance.– Socio-technique models– Soft system methodology– Participatory design
Dept. of Computer Science, Burapha University.
Socio-Technique Model• Socio-Technical models are
concerned with technical, social, organization and human aspect of design.
• They recognize that technology is not developed in isolation but as part of a wider organization environment.
• Objective: to consider social and technical issues side-by-side
Dept. of Computer Science, Burapha University.
Socio-Technique Model• User Skill and Task Match (USTM)
and its form for small organizations CUSTOM
• Open System Task Analysis: OSTA• Effective Technical and Human
Implementation of Computer Systems: ETHICS
Dept. of Computer Science, Burapha University.
USTM/CUSTOM• To allow teams to understand and
fully document user requirements.• It uses diagrammatic task models
together with English descriptions to bring together structured methods and human factors.
Dept. of Computer Science, Burapha University.
USTM/CUSTOM• Focuses on establishing stakeholder
requirements • All Stakeholders are considered, not
just the end-users.• A stakeholder is defined as anyone
who is effected by the success and failure of the system.
Dept. of Computer Science, Burapha University.
USTM/CUSTOM• Primary: those who use the system• Secondary: those who don’t directly use
the system but received output from it• Tertiary: those who do not fall into 1 or 2
but who are affected by the success or failure of the system (directors)
• Facilitating: those who are involved with design, development and maintenance.
Dept. of Computer Science, Burapha University.
USTM/CUSTOM: ExampleAn airline booking system• Primary stakeholder: Travel agency
staff, airline booking staff• Secondary stakeholder: Customers,
airline management• Tertiary stakeholder: Competitor,
civil aviation authorities, customers’travelling companion, airline shareholder
• Facilitating stakeholder: design team, IT department staff.
Dept. of Computer Science, Burapha University.
USTM/CUSTOM: a set of Questions• Describe the organizational context• Identify and describe stakeholder• Identify and describe work-groups• Identify and describe task-object
pairs• Identify stakeholder needs• Consolidate and check stakeholder
requirements
Dept. of Computer Science, Burapha University.
A shorter version of CUSTOM stakeholder Analysis • What does the stakeholder have to
achieve and how is success measured?
• What are the stakeholder’s sources of job satisfaction?
• What are the sources of dissatisfaction and stress?
Dept. of Computer Science, Burapha University.
A shorter version of CUSTOM stakeholder Analysis (cont)• What knowledge and skills does the
stakeholder have?• What is the stakeholder’s attitude
toward and computer technology?• Are there any work-group attribute
that will affect the acceptability of the product to the stakeholder?
Dept. of Computer Science, Burapha University.
A shorter version of CUSTOM stakeholder Analysis (cont)• What are the characteristics of the
stakeholder’s task in term of frequency, fragmentation and choice of action?
• Does the stakeholder have to consider any particular issue relating to responsibility, security or privacy?
• What are the physical conditions in which the stakeholder is working?
Dept. of Computer Science, Burapha University.
Open System Task Analysis: OSTA• Attempts to describe what happens
when a technical system is introduced into an organization work environment.
• The social aspects of the system are specified together with the technical aspects.
Dept. of Computer Science, Burapha University.
OSTA: 8 stages• Technology must identify in term of
user’s goals.• Task inputs to the system are
identified.• External environment is described.• Transformation processes are
described in term of actions performed on or with objects.
Dept. of Computer Science, Burapha University.
OSTA: 8 stages (cont)• Social system is analyzed,
considering existing work-groups and relationship within and external the organization
• Technical system is described in terms of its configuration and integration with other systems.
Dept. of Computer Science, Burapha University.
OSTA: 8 stages (cont)• Performance satisfaction criteria are
established, indicating the social and technical requirements of the system.
• The new technical system is specified.
Dept. of Computer Science, Burapha University.
Effective Technical and Human Implementation of Computer Systems: ETHICS
• Design teams work separately and then attempts to merge their solutions to find the most effective solution which is compatible with both the social and technical requirements
Dept. of Computer Science, Burapha University.
ETHICS 6 stages• The problem is identified and the
current system described• Two design teams are established,
one to examine social aspect, the other technical.
• Alternative social and technical solution are set and evaluated against the criteria already established to determine a short list of possibilities.
Dept. of Computer Science, Burapha University.
ETHICS 6 stages• Solutions from state 3 are checked
for compatibility• Compatible pairs of socio-technical
solutions are ranked according to the criteria already agreed
• Detailed designs are developed.
Dept. of Computer Science, Burapha University.
Soft system methodology• Socio-technique focuses on
identifying requirements from both human and technical perspectives.
• SSM considers of the organization which technology and people are components
Dept. of Computer Science, Burapha University.
Soft system methodology• To help designers reach an
understanding of the context of technological developments.
• SSM has 7 stages– 1-2 and 5-7 are real world stages– 3-4 are system stages
Dept. of Computer Science, Burapha University.
SSM1. Recognition of the problem and initiation
of analysis2. Developing a rich picture
– The tasks they carry out– The work-group they work in– Organizational structure and its processes
and issues– To build a rich picture
• Observation• Structured and un structured interviews and
questionnaires• Workshop incorporating such activities
Dept. of Computer Science, Burapha University.
SSM3. Generate root definition for the
system1. Clients2. Actors3. Transformation4. World view5. Owner6. Environments
Dept. of Computer Science, Burapha University.
SSM4. The conceptual model is devised.
1. Define what the system has to do to fulfil the root definitions.
2. Identifying the transformations and activities in the system and modelling them hierarchically in term of what is achieved and how it is achieved.
3. This process is iterative until it is complete and accurate.
Dept. of Computer Science, Burapha University.
SSM5. Return to real world with our
system6. Compare the actual system with the
conceptual model, identifying discrepancies and thereby highlighting any necessary changes or potential problems
7. Determine which changes are necessary and beneficial to the system as a whole
Dept. of Computer Science, Burapha University.
Participatory design• Design in the workplace• Incorporating the user not only as an
experimental subject but also as a member of the design team
• User are active collaborators in the design process, rather than passive participants whose involvement is entirely governed by the designers.
Dept. of Computer Science, Burapha University.
Characteristics of Participatory design• Makes design and evaluation context
or work oriented rather than system oriented
• Characterized by collaboration: the user is included in the design team and can contribute to every stage of the design
• The approach is iterative
Dept. of Computer Science, Burapha University.
Process of Participatory design• Brainstorming
– Involves all participants in the design pooling ideas
• Storyboarding– Describes the user’s day-to-day
activities as well as the potential designs and the impact they will have
Dept. of Computer Science, Burapha University.
Process of Participatory design• Workshops
– To fill in the missing knowledge of both participants and provide a more focused view of the design
• Pencil and paper exercise– Allow designs to be talked through and
evaluated with very little commitment in term of resources.
Cognitive modelsCognitive modelsCognitive models
Dept. of Computer Science, Burapha University.
Cognitive Model• Model some aspect of the user’s
understanding, knowledge, intentions or processing.
• Level of representations are about keystrokes and mouse clicks.
• Developed by psychologists or computer scientists who interest is in understanding user behaviour.
Dept. of Computer Science, Burapha University.
Quoting from Simon[221]• Competent models tend to be ones
that can be predict legal behaviour sequences but generally do this without reference to whether they could actually be executed by users.
• In contrast, performance models not only describe what the necessary behaviour sequences are but usually describe both what the user needs to know and how this is employed in actual task executions.
Dept. of Computer Science, Burapha University.
Cognitive models• Hierarchical model for
representation of the user’s task and goal structure
• Linguistic and grammatical model• Cognitive architectures
Dept. of Computer Science, Burapha University.
Goal and Task Hierarchies• User achieves goals by solving
subgoals in a divide-and-conquer fashion.
Dept. of Computer Science, Burapha University.
Example: Text Book Sale Reports• Produce report
– Gather data• Find book names
– Do keywords search of names database» Further subgoals
– Sift through names and abstracts by hand» Further subgoals
• Search sales database» Further subgoals
• Layout tables and histograms» Further subgoals
• Write description» Further subgoals
Dept. of Computer Science, Burapha University.
GOMS• Definition of GOMS model:• An approach to describing the
knowledge of procedures that a usermust have in order to operate a system.
• Proposed by Card, Moran, & Newell(1983).
Dept. of Computer Science, Burapha University.
GOMS• Goals - what goals can be
accomplished with the system.• Operators - what basic actions can be
performed.• Methods - what sequences of
operators can be used to accomplisheach goal.
• Selection Rules - which methodshould be used to accomplish a goal.
Dept. of Computer Science, Burapha University.
Example of Methods• To close current window by
– CLOSE pop-up menu or– F10 function key
• GOAL: Iconize-Window– [select
• GOAL: Use-Close-Method– Move-Mouse-to-Window-Header– Pop-up-Menu– Click-Over-Close-Option
• GOAL: Use-F10-Method– Press-F10-Key]
Dept. of Computer Science, Burapha University.
Worked Exercise• Create a GOMS description of task
of photocopying an article from a journal.
Dept. of Computer Science, Burapha University.
Linguistic Model: BNF• Backus-Naur Form• Purely syntactic level, ignoring the
semantics of the languages• Used widely to specify the syntax of
the computer programming languages
Dept. of Computer Science, Burapha University.
BNFDraw-line ::= Select-line + Choose-point
+ Last-pointSelect-line ::= Position-mouse + CLICK-MOUSEChoose-point ::= Choose-one |
Choose-one + Choose-pointChoose-one ::= Position-mouse +
CLICK-MOUSELast-point::= Position-mouse +
DOUBLE-CLICK-MOUSEPosition-mouse ::= empty + MOVE-MOUSE +
Position-mouse
Dept. of Computer Science, Burapha University.
BNF• Non-terminal symbols• Terminal symbols• ‘::=‘ reads ‘is defined as’• ‘+’ (sequence)• ‘|’ (choice)
Dept. of Computer Science, Burapha University.
Worked Exercise• Create a BNF description of task of
photocopying an article from a journal.