MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Lecture 5: Design Strategies/Issues Prototyping MIS 210 Information Systems I

MIS 210 Fall 2004

Lecture 5:Design Strategies/Issues

Prototyping

MIS 210Information Systems I

MIS 210 Fall 2004

Design Strategies/Issues

MIS 210 Fall 2004

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

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


• 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


• Modularity– 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


• Satisficing– “better” not “best” solution– “best” solution not feasible– resource constraints

• Human Interface– human factors– ergonomics

MIS 210 Fall 2004

Output Design

MIS 210 Fall 2004 Sylnovie Merchant, Ph. D.

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


Report Characteristics

• Frequency– How often?

• Periodic

• As required

– ad hoc

– on demand

• Distribution– Who will be using the report?

• Internal

• External

• Turnaround

• Format

MIS 210 Fall 2004

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


Output Design Tactics• Aesthetics

• Strategic value

• Distribution testing– who really needs it?

• Field selection

• Design for change– e.g., field size


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• Right justify numbers, left justify text• Use colors (screen output / color output)

MIS 210 Fall 2004

Input Design


Input Forms

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

MIS 210 Fall 2004

Remember...• A well designed document is…

– easy to use

– unique or specific

– concise

– informative

– expandable

– amenable to data entry

– economical


Human Computer Interaction/Interactive Design


User Types

• Novice• Intermediate• Experienced• Casual (Rusty)


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


Short-term Memory

• Capacity (chunks)– relative to familiarity– Miller’s 7 +/- 2 phenomenon– decreases with anxiety


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


Long-term Memory

• Learning is pushing chunks from STM to LTM

• Takes fair amount of time and iterations

• Once learned, not forgotten


Human Factors Goals

• Time to learn

• Speed of performance

• Rate of user errors

• Subjective satisfaction– turnover rate

• Knowledge retention over time


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


Design Principles • Handle errors civilly.• Allow easy reversal of actions.• Use surprise effectively.• Don’t lose the user.


Keep It Simple

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


Error Checking

• Types Transaction Errors– field type (e.g., numeric)– field size– unreasonable quantity– field not filled in

• mandatory property / slot


Error Checking (continued)• Types (continued)

– logical range (e.g., month)– negative balance– illogical combinations– record access

• not found

• duplicate


Error Checking (continued)

• Catch errors early– cost of rework increases exponentially with time

• Clean Transaction tactic– don’t update records with suspicious data


Error Messages

• Specific and precise

• Constructive– Show what needs to be done– “Transpose Customer #?”

• Positive tone– Avoid “illegal, invalid, bad”


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


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

MIS 210 Fall 2004

Design for Closure

• Break tasks into smallest modules

• Provide user feedback– hourglass– “still processing”– “Phase III completed”

• Keep from discouraging users


Support Internal Locus of Control

• Minimize warnings• No patronizing messages• Avoidance of “we” or “I”• User choices

– color– screen placement– novice / experienced


Easy Reversal of Actions

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


Use Surprise Effectively

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


Screen Structure

• Greeting Screen– Password Screen

• Main Menu– Intermediate Menus

• Function Screens– Form-filling– Transaction update


Structure (Continued)

• Help screens (Pull Down)

• Escape options– Quit– Main Menu– Last screen


Dialogue Modes• Inquiry

– “Are you sure ……”– augments other dialogue modes

• Command Language– experienced user shortcuts

• Menus (for navigation)

• Form-filling Screens


Menus

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

• Number options


Interactive Structure

GreetingGreetingScreenScreen

GreetingGreetingScreenScreen

MainMainMenuMenuMainMainMenuMenu

IntermediateIntermediateMenuMenu


FunctionFunctionScreenScreen


PasswordPasswordScreenScreen

PasswordPasswordScreenScreen









Don’t AcceptDon’t AcceptDon’t AcceptDon’t Accept

AcceptAcceptAcceptAccept

Hel

p S

cree

nsH

elp

Scr

eens

Hel

p S

cree

nsH

elp

Scr

eens

Escape O

ptionsE

scape Options

Escape O

ptionsE

scape Options

(1)(1)(1)(1)

(3)(3)(3)(3)

(4)(4)(4)(4)

(5)(5)(5)(5)

(2)(2)(2)(2)

(6)(6)(6)(6) (7)(7)

(4)(4)(4)(4) (4)(4)(4)(4)

(5)(5)(5)(5) (5)(5)(5)(5)


Form-filling Screens

• Looks like off-line form– same sequence– shade fields to be entered

• Cycle until user chooses to exit

• Maximize transaction throughput


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 #)


Common Screen Considerations

• Highlighting (< 10%)– color– reverse image– flashing– auditory

• Colors (don’t overdo)


Screen Considerations • Symmetry

– unless there’s a reason

• Input verification

• Screen density– Relative screen clutter– Tied to throughput– Total and Local


Total Screen Density

• % 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

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


Local Screen Density

• Mean clutter around each character

• How to reduce– minimize capital letters– limit punctuation– blank lines between text lines– minimize words used


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


Remember

Entertainment is NOT system effectiveness!

MIS 210 Fall 2004

Prototyping


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

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


Approaches

• Type I - Iterative– becomes final system

• Type II - Throwaway– used as model for final system


Type I (Iterative) Life CycleRequirementsRequirements

DefinitionDefinitionRequirementsRequirements

DefinitionDefinitionPrototypePrototypeTrainingTraining

PrototypePrototypeTrainingTraining

ProjectProjectPlanningPlanningProjectProject

PlanningPlanning

Rapid Rapid AnalysisAnalysisRapid Rapid

AnalysisAnalysis

DatabaseDatabaseDesignDesign

DatabaseDatabaseDesignDesign

DesignDesignPrototypePrototype


GenerateGeneratePrototypePrototypeGenerateGeneratePrototypePrototype

TestTestPrototypePrototype


Acceptable?Acceptable?Acceptable?Acceptable?

ImplementImplementSystemSystem

ImplementImplementSystemSystem

MaintainMaintainSystemSystem

MaintainMaintainSystemSystem

NoNoNoNo

YesYesYesYes


Type II (Throwaway) Life Cycle

RequirementsRequirementsDefinitionDefinition

RequirementsRequirementsDefinitionDefinition AnalysisAnalysisAnalysisAnalysis



CodeCodePrototypePrototype

CodeCodePrototypePrototype



Acceptable?Acceptable?Acceptable?Acceptable?

Code FinalCode FinalSystemSystem

Code FinalCode FinalSystemSystem

Test FinalTest FinalSystemSystem

Test FinalTest FinalSystemSystem Acceptable?Acceptable?Acceptable?Acceptable? Implement FinalImplement Final

SystemSystemImplement FinalImplement Final

SystemSystemMaintain FinalMaintain Final

SystemSystemMaintain FinalMaintain Final

SystemSystem

YesYesYesYes

NoNoNoNo

NoNoNoNo

YesYesYesYes

MIS 210 Fall 2004

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


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


Levels (Continued)

• Level 3 (Adaptive)– working model of system– system with training wheels– no bells or whistles


Advantages

• 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


Disadvantages

• Poor documentation

• Hard to control/manage

• (Unrealistic) User expectations– time for final system– final system differences– reduced analysis

Documents

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Lecture 5: Design Strategies/Issues Prototyping MIS 210 Information Systems I