USER INTERFACE
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 theuser's experience and interaction. The goal of user interface design is to make the user's interaction as simple and efficient as possible, in terms of accomplishing user goals—what is often called user-centered design. Good user interface design facilitates finishing the task at hand without drawing unnecessary attention to itself. Graphic design may be utilized to support its usability. The design process must balance technical functionality and visual elements (e.g., mental model) to create a system that is not only operational but also usable and adaptable to changing user needs.
OBJECTIVES:
The main objectives of user interface design are: * To suggest some general design principles for user interface design * To explain different interaction styles and their use * To explain when to use graphical and textual information presentation * To explain the principal activities in the user interface design process (interaction activities) * To introduce usability attributes and approaches to system evaluation
USER INTERFACE: * System users often judge a system by its interface rather than its functionality * A poorly designed interface can cause a user to make catastrophic errors * Poor user interface design is the reason why so many software systems are never used * Most users of business systems interact with these systems through graphical user interfaces (GUIs) * In some cases, legacy text-based interfaces are still used
UI DESIGN PRINCIPLES:
UI design must take account of the needs, experience and capabilities of the system users. Designers should be aware of people’s physical and mental limitations (e.g. limited short-term memory) and should recognise that people make mistakes. UI design principles underlie interface designs although not all principles are applicable to all designs. The main principles include: * User familiarity * The interface should be based on user-oriented terms and concepts rather than computer concepts * E.g., an office system should use concepts such as letters, documents, folders etc. rather than directories, file identifiers, etc. * Consistency * The system should display an appropriate level of consistency * Commands and menus should have the same format, command punctuation should be similar, etc. * Minimal surprise * If a command operates in a known way, the user should be able to predict the operation of comparable commands * Recoverability * The system should provide some resilience to user errors and allow the user to recover from errors * This might include an undo facility, confirmation of destructive actions, 'soft' deletes, etc. * User guidance * Some user guidance such as help systems, on-line manuals, etc. should be supplied * Minimize user effort: the interface should be simple and minimize the number of clicks and keystrokes to move from one part of the system to another * Three click rule * Commonly used by interface designers * User should be able to go from start or main menu of a system to the information or action they want in no more than three mouse clicks or keystrokes * Layout: organization of areas of the screen or document for different purposes * Standard window or Macintosh approach for screen layout * Navigation area (top) * Status area (bottom) * Work area (middle) * Info can be presented in multiple areas * Like areas should be grouped together * Area and information should minimize user movement from one to another * Ideally, area will remain consistent in * Size * Shape * Placement for entering data * Reports presenting retrieved data * Content awareness: users should be aware of where they are in the system and what is being displayed * All interfaces should have titles * Menus should show where you are and where you came from to get there * Clear info must be provided * Fields and field labels must be selected carefully * Aesthetics: designing interfaces that are pleasing to the eye * Interfaces need to be functional and inviting to use * Avoid squeezing in too much * Design text carefully * Be aware of font and size * Avoid using capital letters * Colours and patterns should be used carefully * Test quality of colors by trying the interface on black/white monitor * Use colors to separate or categorize items * User diversity * Interaction facilities for different types of user should be supported * E.g., some users have seeing difficulties and so larger text should be available
UI DESIGN PROCESS:
UI design is an iterative process involving close liaisons between users and designers.
The 3 core activities in this process are: * User analysis: Understand what the users will do with the system; * System prototyping: Develop a series of prototypes for experiment; * Interface evaluation: Experiment with these prototypes with users.

UI DESIGN TECHNIQUES:
Iterative design:
Iterative design offers a way to manage the inherent risk in user interface design. In iterative design, the software is refined by repeated trips around a design cycle: first imagining it (design), then realizing it physically (implementation), then testing it (evaluation).

Problems with iterative design:
• Every iteration corresponds to a release
– Evaluation (complaints) feeds back into next version’s design
• Using your paying customers to evaluate your usability
– They won’t like it
– They won’t buy version 2

Spiral model:
The spiral model offers a way out of the dilemma. We build room for several iterations into our design process, and we do it by making the early iterations as cheap as possible. The radial dimension of the spiral model corresponds to the cost of the iteration step – or, equivalently, its fidelity or accuracy.

Advantages of creating iterative designs using spiral models:
• Early iterations use cheap prototypes
– Parallel design is feasible: build & test multiple prototypes to explore design alternatives
• Later iterations use richer implementations, after UI risk has been mitigated
• Every prototype is evaluated
– Users involved in all iterations
• More iterations generally means better UI
• Only mature iterations are seen by the world
DESIGN ISSUES IN UIs: * Two problems must be addressed in interactive systems design * How should information from the user be provided to the computer system? * How should information from the computer system be presented to the user? * User interaction and information presentation may be integrated through a coherent framework such as a user interface metaphor.
INTERACTION STYLES: * Direct manipulation * Easiest to grasp with immediate feedback * Difficult to program * Menu selection * User effort and errors minimized * Large numbers and combinations of choices a problem * Form fill-in * Ease of use, simple data entry * Tedious, takes a lot of screen space * Command language * Easy to program and process * Difficult to master for casual users * Natural language * Great for casual users * Tedious for expert users
INFORMATION PRESENTATION: * Information presentation is concerned with presenting system information to system users. * The information may be presented directly (e.g. text in a word processor) or may be transformed in some way for presentation (e.g. in some graphical form).

* The Model-View-Controller approach is a way of supporting multiple presentations of data.

Model-View Controller
INFORMATION PRESENTATION: * Static information * Initialised at the beginning of a session. It does not change during the session. * May be either numeric or textual. * Dynamic information * Changes during a session and the changes must be communicated to the system user. * May be either numeric or textual.

ANALOG OR DISITAL PRESENTATION: * Digital presentation * Compact - takes up little screen space; * Precise values can be communicated. * Analogue presentation * Easier to get an 'at a glance' impression of a value; * Possible to show relative values; * Easier to see exceptional data values.
PRESENTATION METHODS:

DISPLAYING RELTIVE VALUES:

TEXTUAL HIGHLIGHTING:

DATA VISUALIZATION: * Concerned with techniques for displaying large amounts of information * Visualisation can reveal relationships between entities and trends in the data * Possible data visualisations are: * Weather information * State of a telephone network * Chemical plant pressures and temperatures * A model of a molecule * Hyperweb
COLOUR DISPLAY: * Colour adds an extra dimension to an interface and can help the user understand complex information structures. * Colour can be used to highlight exceptional events. * Common mistakes in the use of colour in interface design include: * The use of colour to communicate meaning; * The over-use of colour in the display.
Colour use guidelines: * Limit the number of colours used and be conservative in their use. * Use colour change to show a change in system status. * Use colour coding to support the task that users are trying to perform. * Use colour coding in a thoughtful and consistent way. * Be careful about colour pairings.
ERROR MESSAGES: * Error message design is critically important. Poor error messages can mean that a user rejects rather than accepts a system * Messages should be polite, concise, consistent and constructive * The background and experience of users should be the determining factor in message design.
Factors to be kept in mind are: * Context * Experience * Skill level * Style * Culture
System and user oriented error messages:
Assume that a nurse misspells the name of a patient whose records he is trying to retrieve

USER INTERFACE EVALUATION:
Some evaluation of a user interface design should be carried out to assess its suitability. Full scale evaluation is very expensive and impractical for most systems. Ideally, an interface should be evaluated against a usability specification. However, it is rare for such specifications to be produced.

Usability attributes: Attribute | Description | Learnability | How long does it take a new user to become productive with the system? | Speed of operation | How well does the system response match the user’s work practice? | Robustness | How tolerant is the system of user error? | Recoverability | How good is the system at recovering from user errors? | Adaptability | How closely is the system tied to a single model of work? |

Simple evaluation techniques: * Questionnaires for user feedback * Video recording of system use and subsequent tape evaluation. * Instrumentation of code to collect information about facility use and user errors. * Interviewing process. * The provision of a “gripe” button for on-line user feedback.
CONCLUSION:
Interface design should be user-centred. An interface should be logical and consistent and help users recover from errors. Interaction styles include direct manipulation, menu systems form fill-in, command languages, and natural language. Graphical displays should be used to present trends and approximate values. Digital displays when precision is required. Colour should be used sparingly and consistently. Ideally, a user interface should be evaluated against a usability specification. * Systems should provide on-line help. This should include “help, I’m in trouble” and “help, I want information” * A range of different types of user documents should be provided