1. Chapter 12 Designing Interfaces and Dialogues
Modern Systems Analysis and Design Fourth Edition
Chapter 12
Designing Interfaces and Dialogues

2. 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.

4. Interface/Dialogue Design
Layout (of widgets, text, and table data)
Structuring data entry (tab order)
Controlling data input (validation and format controls)
Feedback (prompting, status, warning, and error messages)
Dialogue sequencing

5. Deliverables and Outcomes
A typical interface/dialogue design specification:
Similar to form design, but includes multiple forms and dialogue sequence specifications

6. 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

7. 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

8. 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

12. 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

14. Good Menu Design

15. Visual editing tools help designers construct menus.

16. Form Interaction Measures of an effective design:
Self-explanatory title and field headings
Fields organized into logical groupings
Distinctive boundaries
Default values
Displays appropriate field lengths
Minimizes the need to scroll windows

18. 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

20. 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 viable as other interaction methods

21. Hardware Options for System Interaction
Keyboard
Mouse
Joystick
Trackball
Touch Screen
Light Pen
Graphics Tablet
Voice

22. Usability Problems with Hardware Devices
Adequate Feedback
keyboard, mouse, joystick, trackball, graphics tablet, voice
Speed
keyboard
Pointing Accuracy
joystick, touch screen, light pen, voice
Visual Blocking
touch screen, light pen
User Fatigue
Movement Scaling
keyboard, mouse, joystick, trackball, graphics tablet, voice
Durability
trackball, touch screen

24. 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

25. Structuring Data Entry
Never require data that are already online or that can be computed
Defaults
Always provide default values when appropriate
Units
Make clear the type of data units requested for entry
Replacement
Use character replacement when appropriate
Captioning
Always place a caption adjacent to fields
Format
Provide formatting examples
Justify
Automatically justify data entries
Help
Provide context-sensitive help when appropriate

26. Entering Text

27. 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

28. Types of Validation Tests
Class or Composition
Combinations
Expected Values
Missing Data
Pictures/Templates
Range
Reasonableness
Self-checking Digits
Size
Values

29. 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

30. 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

31. 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

32. Guidelines for Dialogue Design
Consistency
Shortcuts and Sequence
Feedback
Closure
Error Handling
Reversal
Control
Ease

33. Dialogue Diagramming
A formal method for designing and representing human-computer dialogues using box and line diagrams

34. Dialogue diagrams depict the sequence, conditional branching, and repetition of dialogues.

35. 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.

37. 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

38. 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.

39. 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.