MIS 210
Information Systems I
Lecture 5:
Design Strategies/Issues
Prototyping
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Design Strategies/Issues
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Understanding Design Elements
• Design is the process of describing, organizing, and
structuring the components of a system at both the
architectural level and at a detailed level
• Three questions
– What is used for input to the design?
– How is the design done?
– What are the final design documents?
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Principles of Well Designed Systems
• Cohesion
– How well activities within a single module are
related to one another
• Functional cohesion
– containing all, and only, those tasks contributing to the
generation of a single information function/ product
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Principles of Well Designed Systems
• Decoupling
– Separate modules are relatively independent
– loose coupling
• allow one module to be repaired with minimum
disruption to others
– overlapping/duplicate functions
– independence
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Principles of Well Designed Systems
• Modularity
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design of a system in relatively small chunks
allows assignment of developers to different tasks
sections of system can be developed independently
maintenance can occur without disturbing other
modules
• User involvement
– throughout SDLC
– sense of ownership
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Principles of Well Designed Systems
• Satisficing
– “better” not “best” solution
– “best” solution not feasible
– resource constraints
• Human Interface
– human factors
– ergonomics
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Output Design
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Output Design
• Why start with output?
• Output should be:
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accessible
timely
relevant
accurate
usable
complete
correct
secure
economic
efficient
MIS 210
Fall 2004
• Issues:
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output method
output format
purpose
distribution
frequency and timing
Sylnovie Merchant, Ph. D.
Report Characteristics
• Frequency
• Distribution
– How often?
– Who will be using the report?
• Periodic
• As required
– ad hoc
– on demand
• Internal
• External
• Turnaround
• Format
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Report Types
• Detail
• Summary (Management)
– day to day operations
– structured
– statistics and ratios
– ad hoc or periodic
– structured
• Resource status
– inventory, customer activity, etc.
– periodic (e.g.,once a month)
– structured or unstructured
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Output Design Tactics
• Aesthetics
• Strategic value
• Distribution testing
– who really needs it?
• Field selection
• Design for change
– e.g., field size
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Principles of Output Design
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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
Right justify numbers, left justify text
Use colors (screen output / color output)
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Input Design
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Input Forms
Forms of input
– manual paper forms
– electronic input forms
– direct-entry devices
– document image processing
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Remember...
• A well designed document is…
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easy to use
unique or specific
concise
informative
expandable
amenable to data entry
economical
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Human Computer Interaction/
Interactive Design
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
User Types
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MIS 210
Novice
Intermediate
Experienced
Casual (Rusty)
Fall 2004
Sylnovie Merchant, Ph. D.
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
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Short-term Memory
• Capacity (chunks)
– relative to familiarity
– Miller’s 7 +/- 2 phenomenon
– decreases with anxiety
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
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
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Long-term Memory
• Learning is pushing chunks from STM
to LTM
• Takes fair amount of time and iterations
• Once learned, not forgotten
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Human Factors Goals
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Time to learn
Speed of performance
Rate of user errors
Subjective satisfaction
– turnover rate
• Knowledge retention over time
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Design Principles
(Shneiderman, 1987)
• Keep it simple.
• Be consistent.
• Design tasks for closure.
• Support internal locus of control.
• Provide user shortcuts
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Design Principles
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MIS 210
Handle errors civilly.
Allow easy reversal of actions.
Use surprise effectively.
Don’t lose the user.
Fall 2004
Sylnovie Merchant, Ph. D.
Keep It Simple
• Simple screen designs
• Minimal use of windows
• Screen density
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Error Checking
• Types Transaction Errors
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field type (e.g., numeric)
field size
unreasonable quantity
field not filled in
• mandatory property / slot
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Error Checking (continued)
• Types (continued)
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logical range (e.g., month)
negative balance
illogical combinations
record access
• not found
• duplicate
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Error Checking (continued)
• Catch errors early
– cost of rework increases exponentially with time
• Clean Transaction tactic
– don’t update records with suspicious data
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Error Messages
• Specific and precise
• Constructive
– Show what needs to be done
– “Transpose Customer #?”
• Positive tone
– Avoid “illegal, invalid, bad”
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
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
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Be Consistent
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Same terminology on all screens
Similar screen layouts
Standard escape routes
Consistent processing times
– novice users prefer consistent, not faster,
screen response times
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Design for Closure
• Break tasks into smallest modules
• Provide user feedback
– hourglass
– “still processing”
– “Phase III completed”
• Keep from discouraging users
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Support Internal Locus of Control
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Minimize warnings
No patronizing messages
Avoidance of “we” or “I”
User choices
– color
– screen placement
– novice / experienced
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Easy Reversal of Actions
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MIS 210
Erase / undo
Word / Line / Screen
Escape menus
Paging back
Fall 2004
Sylnovie Merchant, Ph. D.
Use Surprise Effectively
• Minimum highlighting
• Minimum input verification
• Few flashing or auditory signals
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Screen Structure
• Greeting Screen
– Password Screen
• Main Menu
– Intermediate Menus
• Function Screens
– Form-filling
– Transaction update
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Structure (Continued)
• Help screens (Pull Down)
• Escape options
– Quit
– Main Menu
– Last screen
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Dialogue Modes
• Inquiry
– “Are you sure ……”
– augments other dialogue modes
• Command Language
– experienced user shortcuts
• Menus (for navigation)
• Form-filling Screens
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Menus
• Option sequence
– logical (new, update, delete)
– frequency of choice
– alphabetic
• Number options
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Interactive Structure
(1)
Greeting
Screen
Don’t Accept
Accept
(4)
(5)
(6)
MIS 210
Intermediate
Menu
Function
Screen
(4)
(5)
Password
Screen
Main
Menu
Intermediate
Menu
Function
Screen
Fall 2004
(4)
(5)
Escape Options
Help Screens
(3)
(2)
Intermediate
Menu
Function
Screen
(7)
Sylnovie Merchant, Ph. D.
Form-filling Screens
• Looks like off-line form
– same sequence
– shade fields to be entered
• Cycle until user chooses to exit
• Maximize transaction throughput
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Maximizing Transaction Throughput
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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 #)
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Common Screen Considerations
• Highlighting (< 10%)
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color
reverse image
flashing
auditory
• Colors (don’t overdo)
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Screen Considerations
• Symmetry
– unless there’s a reason
• Input verification
• Screen density
– Relative screen clutter
– Tied to throughput
– Total and Local
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Total Screen Density
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% screen with non-blank characters
(# char) / (screen capacity)
should be < 25%
can achieve on form-filling screen
– dimming unused screen portions
– highlighting screen portions
– blocking out with windows
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Example
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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
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Local Screen Density
• Mean clutter around each character
• How to reduce
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minimize capital letters
limit punctuation
blank lines between text lines
minimize words used
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Features That Affect User Interface Design
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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
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Remember
Entertainment is NOT system effectiveness!
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Prototyping
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Definition
• A PROTOTYPE is a model of the system
– It can be as simple as mock-ups of reports or
screens, or as complete as software that actually
does some processing.
– Can be used as a communication tool between
analyst and user.
• Prototyping is the process of developing
prototypes.
• Prototyping strategy indicates the type of
prototype used.
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Why Prototyping
“When you’re working with new system
ideas with your users, you don’t want to go
through the cost of developing a gigantic
system which might take years; you’ll build
a mock-up of it, which might take weeks.”
Brian Kilcourse, CIO
Longs Drug Stores
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Approaches
• Type I - Iterative
– becomes final system
• Type II - Throwaway
– used as model for final system
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Type I (Iterative) Life Cycle
Requirements
Definition
Prototype
Training
Project
Planning
Rapid
Analysis
Database
Design
Design
Prototype
Generate
Prototype
Test
Prototype
No
Acceptable?
Yes
Implement
System
Maintain
System
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Type II (Throwaway) Life Cycle
Requirements
Definition
Analysis
Design
Prototype
Code
Prototype
Test
Prototype
Acceptable?
No
Yes
Code Final
System
Test Final
System
MIS 210
No
Acceptable?
Fall 2004
Yes
Implement Final
System
Maintain Final
System
Sylnovie Merchant, Ph. D.
Types of Prototypes
• Illustrative
– Mock-ups
• Simulated
– Looks like they work, but are simulations
• Functional
– Does some processing, but doesn’t store data
• Evolutionary
– Used to produce an operational systems
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Prototype Levels
• Level 1 (Input-Output)
– printed reports and on-line screens
– screen flow sequence
– screen options
• Level 2 (Heuristic-Learning)
– updating database
– basic transactions
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Levels (Continued)
• Level 3 (Adaptive)
– working model of system
– system with training wheels
– no bells or whistles
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Advantages
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Speed
Easier for end-users to learn
System changes discovered earlier
End-user involvement (ownership)
– increased user satisfaction
– increased user acceptance
• User-analyst communication
• Early problem detection
– reduced development time
– reduced maintenance
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.
Disadvantages
• Poor documentation
• Hard to control/manage
• (Unrealistic) User expectations
– time for final system
– final system differences
– reduced analysis
MIS 210
Fall 2004
Sylnovie Merchant, Ph. D.