User Interface Design-Software egineering

User Interface Design

Interface Design

Easy to learn ?

Easy to use?

Easy to understand?

Typical Design Errors

• Lack of consistency
• Too much memorization
• No guidance / help
• No context sensitivity
• Poor response
• Unfriendly

Golden Rules

• Place the user in control
• Reduce the user’s memory load
• Make the interface consistent

Place the User in Control

• Provide for flexible interaction.
• Streamline interaction as skill levels advance and allow the interaction to be customized.
• Hide technical internals from the casual user.
• Design for direct interaction with objects that appear on the screen.

Reduce the User’s Memory Load

• Reduce demand on short-term memory.
• Establish meaningful names.
• Define shortcuts.
• The visual layout of the interface should be based on a real world metaphor.
• Disclose information in a progressive fashion.

Make the Interface Consistent

• Allow the user to put the current task into a meaningful context.
• Maintain consistency across a family of applications.
• If past interactive models have created user expectations, do not make changes unless there is a compelling reason to do so.

User Interface Design Models

• User model — a profile of all end users of the system
• Design model — a design realization of the user model
• Mental model (system perception) the user’s mental image of what the interface is
• Implementation model — the interface look and feel coupled with supporting information that describe interface syntax and semantics

User Interface Design Process

Interface Analysis

Interface analysis means understanding :

• the people (end-users) who will interact with the system through the interface
• the tasks that end-users must perform to do their work,
• the content that is presented as part of the interface
• the environment in which these tasks will be conducted.

• Are users trained professionals, technician, or manufacturing workers?
• What level of formal education does the average user have?
• Are the users capable of learning from written materials or have they expressed a desire for classroom training?
• Are users expert typists or keyboard phobic?
• What is the age range of the user community?
• How are users compensated for the work they perform?
• Do users work normal office hours or do they work until the job is done?
• What is the primary spoken language among users?
• What are the consequences if a user makes a mistake using the system?
• Are users experts in the subject matter that is addressed by the system?
• Do users want to know about the technology the sits behind the interface?

Task Analysis and Modeling

Task Analysis answers the following questions …

• What work will the user perform in specific circumstances?
• What tasks and subtasks will be performed as the user does the work?
• What specific problem domain objects will the user manipulate as work is performed?
• What is the sequence of work tasks—the workflow?
• Workflow analysis defines how a work process is completed when several people (and roles) are involved
• What is the hierarchy of tasks?
• Use-cases define basic interaction

Analysis of Display Content

• Are different types of data assigned to consistent geographic locations on the screen (e.g., photos always appear in the upper right hand corner)?
• Can the user customize the screen location for content?
• Is proper on-screen identification assigned to all content?
• If a large report is to be presented, how should it be partitioned for ease of understanding?
• Will graphical output be scaled to fit within the bounds of the display device that is used?
• How will color to be used to enhance understanding?
• How will error messages and warning be presented to the user?

Design Evaluation Cycle

Interface Design Patterns

• Patterns are available for

–The complete UI

–Page layout

–Forms and input

–Tables

–Searching

–Page elements

–e-Commerce

Design Issues

• Response time
• Help facilities
• Error handling
• Menu
• Application accessibility