User Interface

1
User Interface

• Lecture 8
• Spring 2004

2
Traditional Design Principles

• Our Textbook, Chapter 11, does a good job
  describing Design Principles
• What follows are Professor Sylnovie Merchants
  slides on this topic
• Beware, however, that this area is one of
  constant reinvention and creativity and that
  strict adherence to principles is not necessarily
  a source of competitive advantage.

3
Beware that User Interface Design requires both
Art and Science.Strict adherence to
principles is not necessarily a source of
competitive advantage.Creative application (and
mis-application) of the principles can and often
does yield successful designs. One must master
the principles and then learn how and when to
break them.
4
Output Design
Source Professor Merchant
5
Output Design

• Why start with output?
• Output should be
• accessible
• timely
• relevant
• accurate
• usable
• complete
• correct
• secure
• economic
• efficient

• Issues
• output method
• output format
• purpose
• distribution
• frequency and timing

Source Professor Merchant
6
Report Characteristics

• Frequency
• How often?
• Periodic
• As required
• ad hoc
• on demand
• Distribution
• Who will be using the report?
• Internal
• External
• Turnaround
• Format

Source Professor Merchant
7
Report Types

• Detail
• day to day operations
• structured
• Resource status
• inventory, customer activity, etc.
• periodic (e.g.,once a month)
• structured or unstructured

• Summary (Management)
• statistics and ratios
• ad hoc or periodic
• structured

Source Professor Merchant
8
Output Design Tactics

• Aesthetics
• Strategic value
• Distribution testing
• who really needs it?
• Field selection
• Design for change
• e.g., field size

Source Professor Merchant
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Principles of Output Design

• Always have a title (proper wording, page
  numbers, dates)
• Use sections
• Include legends
• Eliminate computer jargon
• Read left to right, top to bottom
• Column headings for multi-record layout
• Data labels for single record layout
• Leave 3 spaces between data fields
• Leave 5 spaces between data labels
• Right justify numbers, left justify text
• Use colors (screen output / color output)

Source Professor Merchant
10
Input Design
Source Professor Merchant
11
Input Forms

• Forms of input
• manual paper forms
• electronic input forms
• direct-entry devices
• document image processing

Source Professor Merchant
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Remember...

• A well designed document is
• easy to use
• unique or specific
• concise
• informative
• expandable
• amenable to data entry
• economical

Source Professor Merchant
13
Human Computer Interaction/Interactive Design
Source Professor Merchant
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User Types

• Novice
• Intermediate
• Experienced
• Casual (Rusty)

Source Professor Merchant
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The Novice User

• Human Factors default
• experienced users get testy
• novice users quit
• Why cater to them when they learn so quickly?
• Typical turnover rate

Source Professor Merchant
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Short-term Memory

• Capacity (chunks)
• relative to familiarity
• Millers 7 /- 2 phenomenon
• decreases with anxiety

Source Professor Merchant
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STM Volatility

• Limited capacity
• Data lasts about 15 sec
• Events causing data loss
• interruption (phone calls)
• processing delays (response time)
• visual distraction (color)
• noisy work environment
• Importance of closure

Source Professor Merchant
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Long-term Memory

• Learning is pushing chunks from STM to LTM
• Takes fair amount of time and iterations
• Once learned, not forgotten lose access keys
• if new chunks pictorially similar

Source Professor Merchant
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Human Factors Goals

• Time to learn
• Speed of performance
• Rate of user errors
• Subjective satisfaction
• turnover rate
• Knowledge retention over time

Source Professor Merchant
20
Design Principles

• (Shneiderman, 1987)
• Keep it simple.
• Be consistent.
• Design tasks for closure.
• Support internal locus of control.
• Provide user shortcuts

Source Professor Merchant
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Design Principles

• Handle errors civilly.
• Allow easy reversal of actions.
• Use surprise effectively.
• Dont lose the user.

Source Professor Merchant
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Keep It Simple

• Simple screen designs
• Minimal use of windows
• Screen density

Source Professor Merchant
23
Error Checking

• Types Transaction Errors
• field type (e.g., numeric)
• field size
• unreasonable quantity
• field not filled in
• mandatory property / slot

Source Professor Merchant
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Error Checking (continued)

• Types (continued)
• logical range (e.g., month)
• negative balance
• illogical combinations
• record access
• not found
• duplicate

Source Professor Merchant
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Error Checking (continued)

• Catch errors early
• cost of rework increases exponentially with time
• Clean Transaction tactic
• dont update records with suspicious data

Source Professor Merchant
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Error Messages

• Specific and precise
• Constructive
• Show what needs to be done
• Transpose Customer ?
• Positive tone
• Avoid illegal, invalid, bad

Source Professor Merchant
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Error Messages (continued)

• User-centered phrasing
• Ready for data rather than
• Enter data
• Multiple levels of messages
• Help Specific screens
• Consistent grammatical form, terminology and
  abbreviations

Source Professor Merchant
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Be Consistent

• Same terminology on all screens
• Similar screen layouts
• Standard escape routes
• Consistent processing times
• novice users prefer consistent,
• not faster,
• screen response times

Source Professor Merchant
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Design for Closure

• Break tasks into smallest modules
• Provide user feedback
• hourglass
• still processing
• Phase III completed
• Short-term memory capacity
• Keep from discouraging users

Source Professor Merchant
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Design for Closure

• Break tasks into smallest modules
• Provide user feedback
• hourglass
• still processing
• Phase III completed
• Short-term memory capacity
• Keep from discouraging users

Source Professor Merchant
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Design for Closure

• Break tasks into smallest modules
• Provide user feedback
• hourglass
• still processing
• Phase III completed
• Short-term memory capacity
• Keep from discouraging users

Source Professor Merchant
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Support Internal Locus of Control

• Minimize warnings
• No patronizing messages
• Avoidance of we or I
• User choices
• color
• screen placement
• novice / experienced

Source Professor Merchant
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Easy Reversal of Actions

• Erase / undo
• Word / Line / Screen
• Escape menus
• Paging back

Source Professor Merchant
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Use Surprise Effectively

• Minimum highlighting
• Minimum input verification
• Few flashing or auditory signals

Source Professor Merchant
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Screen Structure

• Greeting Screen
• Password Screen
• Main Menu
• Intermediate Menus
• Function Screens
• Form-filling
• Transaction update

Source Professor Merchant
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Structure (Continued)

• Help screens (Pull Down)
• Escape options
• Quit
• Main Menu
• Last screen

Source Professor Merchant
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Dialogue Modes

• Inquiry
• Are you sure
• augments other dialogue modes
• Command Language
• experienced user shortcuts
• Menus (for navigation)
• Form-filling Screens

Source Professor Merchant
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Menus

• Option sequence
• logical (new, update, delete)
• frequency of choice
• alphabetic
• Number options

Source Professor Merchant
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Interactive Structure
Greeting Screen
(1)
Dont Accept
(2)
Password Screen
Accept
(3)
Main Menu
Help Screens
Escape Options
(4)
(4)
(4)
Intermediate Menu
Intermediate Menu
Intermediate Menu
(5)
(5)
(5)
Function Screen
Function Screen
Function Screen
(6)
(7)
Source Professor Merchant
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Form-filling Screens

• Looks like off-line form
• same sequence
• shade fields to be entered
• Cycle until user chooses to exit
• Maximize transaction throughput

Source Professor Merchant
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Maximizing Transaction Throughput

• Cueing (entry format)
• Autoterminate
• Free-form entry
• Default values
• constant (e.g., System Date)
• from record (e.g., Item Price)
• last transaction (e.g., Cust )

Source Professor Merchant
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Common Screen Considerations

• Highlighting (lt 10)
• color
• reverse image
• flashing
• auditory
• Colors (dont overdo)

Source Professor Merchant
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Screen Considerations

• Symmetry
• unless theres a reason
• Input verification
• Screen density
• Relative screen clutter
• Tied to throughput
• Total and Local

Source Professor Merchant
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Total Screen Density

• screen with non-blank characters
• ( char) / (screen capacity)
• should be lt 25
• can achieve on form-filling screen
• dimming unused screen portions
• highlighting screen portions
• blocking out with windows

Source Professor Merchant
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Example

• Non-zero characters
• Filling up the screen
• From top to bottom
• From left margin to right margin
• Too much total screen density
• Novice users will have reduced throughput

Source Professor Merchant
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Local Screen Density

• Mean clutter around each character
• How to reduce
• minimize capital letters
• limit punctuation
• blank lines between text lines
• minimize words used

Source Professor Merchant
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Features That Affect User Interface Design

• Display area
• Character sets and graphics
• Paging and scrolling
• Color displays and display properties
• Split-screen and windowing capabilities
• Keyboards and function keys
• Pointer options

Source Professor Merchant
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Remember

• Entertainment is NOT system effectiveness!

Source Professor Merchant