Models of the User in Desing

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


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


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


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


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.


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.


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.


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.


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


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?


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?


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?


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.


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.


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.


OSTA: 8 stages (cont)• Performance satisfaction criteria are

established, indicating the social and technical requirements of the system.

• The new technical system is specified.


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


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.


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.


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


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


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


SSM3. Generate root definition for the

system1. Clients2. Actors3. Transformation4. World view5. Owner6. Environments


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.


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


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.


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


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


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


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.


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.


Cognitive models• Hierarchical model for

representation of the user’s task and goal structure

• Linguistic and grammatical model• Cognitive architectures


Goal and Task Hierarchies• User achieves goals by solving

subgoals in a divide-and-conquer fashion.


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


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).


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.


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]


Worked Exercise• Create a GOMS description of task

of photocopying an article from a journal.


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


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


BNF• Non-terminal symbols• Terminal symbols• ‘::=‘ reads ‘is defined as’• ‘+’ (sequence)• ‘|’ (choice)


Worked Exercise• Create a BNF description of task of

photocopying an article from a journal.

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Models of the User in Desing