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Modern Systems Analysis and Design Fourth Edition Jeffrey A. Hoffer Joey F. George Joseph S. Valacich. Chapter 12 Designing Interfaces and Dialogues. Learning Objectives. Explain the process of interface and dialogue design. Contrast and apply methods for interacting with a system.
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Modern Systems Analysisand DesignFourth EditionJeffrey A. Hoffer Joey F. GeorgeJoseph S. Valacich Chapter 12 Designing Interfaces and Dialogues
Learning Objectives • Explain the process of interface and dialogue design. • Contrast and apply methods for interacting with a system. • List and describe various input devices and factors affecting their usability. • Describe guidelines for designing interface layout, data entry field structure, feedback, and system help. • Design graphical user interfaces.
Interface/Dialogue Design • Layout (of text, and table data) • Structuring data entry • Controlling data input (validation and format controls) • Feedback (prompting, status, warning, and error messages) • Dialogue sequencing
Deliverables and Outcomes A typical interface/dialogue design specification: Similar to form design, but includes multiple forms and dialogue sequence specifications
Characteristics for Consideration • User: experience, skills, motivation, education, personality • Tasks: differ in amount of information that must be obtained or provided • Task demands: time pressure, cost of errors, work durations (fatigue) • System: the platform on which the system is constructed will influence interaction styles and devices. • Environment: • social issues: user’s role and status • physical issues: lighting, sound, task interruptions, temperature, humidity
Interface Methods • Interface: the method by which a user interacts with the information system • Common interaction methods • Command line • Menu • Form • Object-based • Natural language
Command Line Interaction • Users enter explicit statements into a system to invoke operations • Example from MS DOS: • COPY C:PAPER.DOC A:PAPER.DOC • This copies a file from the C: drive to the A: drive • Includes keyboard shortcuts and function keys
Interface Methods • Interface: the method by which a user interacts with the information system • Common interaction methods • Command line • Menu • Form • Object-based • Natural language
Menu Interaction • A list of system options is provided and specific command is invoked by user selection of a menu option • Two common menu types: • Pop-up: menu placed near current cursor position • Drop-down: access point to menu placed at top line of display, menu drops down when access point clicked
Guidelines for Menu Design • Wording: meaningful titles, clear command verbs, mixed upper/lower case • Organization: consistent organizing principle • Length: all choices fit within screen length • Selection: consistent, clear and easy selection methods • Highlighting: only for selected options or unavailable options (gray text)
Interface Methods • Interface: the method by which a user interacts with the information system • Common interaction methods • Command line • Menu • Form • Object-based • Natural language
Form Interaction • Allows users to fill in the blanks when working with a system • Measures of an effective design: • Self-explanatory title and field headings • Fields organized into logical groupings • Distinctive boundaries • Default values • Displays appropriate fieldlengths • Minimizes the need to scroll windows
Interface Methods • Interface: the method by which a user interacts with the information system • Common interaction methods • Command line • Menu • Form • Object-based • Natural language
Object Interaction • Symbols are used to represent commands or functions. • Icons: • Graphic symbols that look like the processing option they are meant to represent • Use little screen space • Can be easily understood by users
Interface Methods • Interface: the method by which a user interacts with the information system • Common interaction methods • Command line • Menu • Form • Object-based • Natural language
Natural Language Interaction • Inputs to and outputs from system are in a conventional speaking language like English • Based on research in artificial intelligence • Current implementations are tedious and difficult to work with, not as feasible as other interaction methods
Keyboard Mouse Joystick Trackball Touch Screen Light Pen Graphics Tablet Voice Hardware Options for System Interaction
Visual Blocking (device blocks display when using) touch screen, light pen User Fatigue (potential for fatigue over long use) touch screen, light pen Movement Scaling (device movement translates to equivalent screen movement) keyboard, mouse, joystick, trackball, graphics tablet, voice Durability (need for maintenance) trackball, touch screen Adequate Feedback (device provides adequate feedback) keyboard, mouse, joystick, trackball, graphics tablet, voice Speed (cursor movement) keyboard Pointing Accuracy (ability to precisely direct cursor joystick, touch screen, light pen, voice Usability Problems with Hardware Devices
Designing Interfaces • Use standard formats similar to paper-based forms and reports • Left-to-right, top-to-bottom navigation • Flexibility and consistency: • Free movement between fields • No permanent data storage until the user requests • Each key and command assigned to one function
Controlling Data Input • Objective: reduce data entry errors • Common sources data entry errors in a field: • Appending: adding additional characters • Truncating: losing characters • Transcripting: entering invalid data • Transposing: reversing sequence of characters
Class or Composition Type check Combinations Check if reasonable, E.g.: quantity of sold + type of product? Expected Values E.g. Match with existing customer Missing Data E.g. All fields of a record Pictures/Templates Standard format, E.g.hyphens … Types of Validation Tests
Range • Reasonableness • For situation • Self-checking Digits • Size • 9 digit ID • Values • Come from set of standards: Two-letter state code
Feedback Messages • Status information: keep user informed of what’s going on, helpful when user has to wait for response • Prompting cues: tell user when input is needed, and how to provide the input • Warning or Error: inform user that something is wrong, either with data entry or system operation
Providing Help • Place yourself in user’s place when designing help • Guidelines: • Simplicity • Help messages should be short and to the point • Organize • Information in help messages should be easily absorbed by users • Show • It is useful to explicitly show users how to perform an operation
What is a Dialogue? • A sequence of interactions between the system and a user • Dialogue design involves: • Designing a dialogue sequence • Building a prototype • Assessing usability
Consistency Shortcuts and Sequence Feedback Closure (clear start, and end) Error Handling Reversal Control Ease Guidelines for Dialogue Design
Dialogue Diagramming A formal method for designing and representing human-computer dialogues using box and line diagrams
Dialogue diagrams depict the sequence, conditional branching, and repetition of dialogues.
Designing Interfaces and Dialogues in Graphical Environments • Become an expert user of the GUI environment. • Understand how other applications have been designed. • Understand standards. • Gain an understanding of the available resources and how they can be used. • Become familiar with standards for menus and forms.
GUI Window Properties That Can Be Turned On or Off • Modality: require user to finish action before proceeding • Resizable: allow user to change size of window • Movable: allow user to reposition window • Maximize: allow user to make window take entire screen • Minimize: allow user to completely hide window • System menu: allow window to have access to system level functions
GUI Dialogue Design Issues • Goal is to establish the sequence of displays that users will encounter when working with system. • Ability of some GUI environments to jump from application to application or screen to screen makes sequencing a challenge. • One approach is to make users always resolve requests for information before proceeding. • Dialogue diagramming helps analysts better manage the complexity of designing graphical interfaces.
Summary • In this chapter you learned how to: • Explain the process of interface and dialogue design. • Contrast and apply methods for interacting with a system. • List and describe various input devices and factors affecting their usability. • Describe guidelines for designing interface layout, data entry field structure, feedback, and system help. • Design graphical user interfaces.