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INTRODUCTION USER INTERFACE DESIGN

❖ User interface design or user interface engineering is the design of computers, appliances, machines, mobile communication devices, software applications, and

websites with the focus on the user's experience and interaction. The goal of user interface design is to make the user's interaction as simple and efficient as possible.

❖ User-interface design, which has remarkable diverse communities, stems from a desire to improve the user experience.

Eg :

In business settings, better decision-support and desktop-publishing tools support entrepreneurs.

In home settings digital photos and voice messaging enhance family relationships.

A significant number of people take advantage of the World Wide Web’s remarkable educational and cultural heritage resources, e-government services and health support communities.

Usability Requirements :

Every designer wants to build high-quality interfaces that are admired by colleagues, celebrated by users, and imitated frequently.

Appreciation comes from inherent quality features such as usability, universality and usefulness.

These goals are achieved through thoughtful planning, sensitivity to user needs, devotion to requirement analysis and diligent(thorough) testing.

Managers can promote attention to user-interface design by selection of personnel, preparation of schedules and milestones , construction and application of guidelines documents and commitment to testing.

Effective interfaces generate positive feelings of success , competence, mastery and clarity in the user community.

Setting explicit goals helps to achieve these requirements.

The U.S. Military Standard for Human Engineering Design Criteria states these purposes :

1. Achieve required performance operator, control, maintenance personnel. 2. Minimize skill, personnel requirements and training time.

3. Achieve reliability of personnel-equipment/software combinations 4. Encourage the design standardization within the systems.

1. First goal Determine the user needs. What tasks and subtasks to be carried out.

Frequent task are easy to determine but the exceptional tasks for emergency conditions

and the repair tasks to cope with errors in use of the interface are more difficult to discover.

Providing excessive functionality is difficult because the confusion makes the implementation, maintenance, learning and usage more difficult.

2. Ensure Proper Reliability

Action must function as specified, displayed data must reflect the database contents and

updates must be applied correctly.

Designers must also pay attention to ensuring privacy, security and data integrity. Protection must be provided from unauthorized access and accidental destruction of data.

The software architecture, hardware components and network support must ensure high availability.

3.

Promote appropriate standardization, integration , consistency

and portability:

Standardization : refers to common user interface features across multiple applications.

Slight differences between interfaces increases learning time and lead to annoying and dangerous errors.

Gross differences between interfaces require substantial retraining.

Eg : Microsoft Windows

The standards of World Wide Web consortium helps for easy usage of web.

ISO produces standards for “Ergonomics Requirements for Office Work with Visual Display

Terminals” covers displays, menus, keyboards, work environments.

Integration : across application packages and software tools was one of the key design

principles of UNIX.

If consistent file formats are used , users can apply multiple applications to transform, refine

Consistency

Consistency is a strong determinant of success of interfaces.

Compatibility across application programs and compatibility with paper or non-computer-based systems is also there.

Portability refers to convert data and to share user interfaces across multiple software and hardware environments.

Challenge for designers to handle different display sizes, resolutions, color capabilities, pointing devices and data formats..etc.

4. Complete Projects on schedule and within budget :

If an in-house(internal) system is delivered late, other projects may be affected and the disruption(trouble)may cause managers to choose to install an alternative system.

If a commercial system is too costly, customer resistance may emerge to prevent widespread acceptance, allowing competitors to capture the market.

Proper attention to usability principles and rigorous testing often lead to reduced cost and rapid development.

A carefully tested design generates fewer changes during implementation and avoids costly updates after release.

Usability Measures :

Developers can focus their attention on the design and testing process.

Multiple design alternatives must be evaluated for different user communities .

A clever design for one community of users may be inappropriate for another community.

Eg : Separate interfaces were created for cataloging new books and searching the online book catalog.

It was impossible to say which was better because both were fine interfaces but they were serving different needs.

Touchscreen interface with reduced functionality and better information presentation

The ISO 9241 standard focuses on admirable goals :

Effectiveness , Efficiency

and Satisfaction

1. Time to learn : How long does it takes for the user to learn how to use the actions

relevant to a set of tasks.?

2. Speed Of Performance : How long does it take to carry out the benchmark

tasks.?(standard/target)

3. Rate Of Errors By Users : How many and what kinds of errors do people make in

carrying out the benchmark tasks.?

4. Retention(Maintenance) Over Time : This is closely linked to time to learn and

Requirements documents and marketing brochures that make clear which goals are primary are more likely to be valued.

eg :

If a rate of errors is to be kept extremely low , speed of performance may have to be sacrificed.

In some applications , subjective satisfaction is the key determinant of success, in others short learning times or rapid performance may be important.

In short, the user manuals and the online help can be written before the implementation. It provides another review and perspective on the design.

Implementation should be carried out with proper software tools.

The acceptance test certifies that the delivered interface meets the goals of the designers and customers.

Usability Motivations :

⚫ The interest in interface usability arises due to the difference in poorly designed interfaces and of the benefits elegant interfaces bring to users.

⚫ This increased motivation comes from developers of life-critical systems, industrial and commercial systems, office, home and entertainment applications…,etc.

⚫ Life-Critical Systems :

⚫ Life-critical systems include those that control air traffic, nuclear reactors, power utilities, police or fire dispatch, military operations and medical instruments.

⚫ It cost high as High reliability and effectiveness is needed.

⚫ Lengthy training periods are acceptable to obtain rapid, error-free performance.

• Maps

Easily search maps and satellite images.

⚫ Driving Directions

Instantly get text and map driving directions.

⚫ Real Time Traffic Reports

Check on the traffic and plan the fastest route.

Weather Forecast

Get local weather automatically and weather by location.

Industrial and Commercial Uses :

These include banking, insurance, order entry, inventory management, airline and hotel reservations, car rentals, utility billing, credit-card management, point-of-sales terminals.

Operator training time is expensive, so ease of learning is important.

Subjective satisfaction is of modest importance, retention is obtained by frequent use.

Speed of performance is important because of the high volume of transactions but operator fatigue and stress should also be considered.

Office, home and entertainment applications :

Personal-computing applications include email, bank machines, games, educational packages, search engines, cell phones and mobile devices.

Eg : design of search engines which almost always have a basic and advanced interface.

Low cost is another important goal because of lively competition.

Exploratory, creative, and collaborative interfaces :

Exploratory(investigative/examining) applications include World Wide Web browsing,

search engines, scientific simulation and business decision making.

Creative environments include writing workbenches, architectural design systems, artist or

programmer workstations, and music-composition systems.

Collaborative interfaces enable two or more people to work together, even if the users are

separated by time and space, through use of electronic text, voice and video mail. Eg : skype

Through electronic meeting systems that facilitate face-to-face meetings or through groupware

that enables remote collaborators to work concurrently on a document, map, spreadsheet or

Sociotechnical systems :

A growing domain for usability is in complex systems that involve many people over long time periods, such as systems for voting, health support, identity verification and crime reporting.

Interfaces for these systems have to deal with trust, privacy and responsibility as well as

limiting the harmful effects of malicious tampering, deception(cheating), and incorrect information.

Users want access to verifiable sources, adequate feedback about their actions, and ways of easily checking status.

Eg : In electronic voting systems citizens need to have reassuring feedback that their votes were correctly recorded, possibly by having a printed receipt.