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

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Design Strategies/Issues

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Principles of Well Designed Systems 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Output Design

MIS 210 Fall 2004Sylnovie 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

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. 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 2004Sylnovie Merchant, Ph. D. 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

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. 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 2004Sylnovie Merchant, Ph. D. Input Design

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Input Forms Forms of input –manual paper forms –electronic input forms –direct-entry devices –document image processing

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Remember... A well designed document is… –easy to use –unique or specific –concise –informative –expandable –amenable to data entry –economical

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Human Computer Interaction/ Interactive Design

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. User Types Novice Intermediate Experienced Casual (Rusty)

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Short-term Memory Capacity (chunks) –relative to familiarity –Miller’s 7 +/- 2 phenomenon –decreases with anxiety

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Human Factors Goals Time to learn Speed of performance Rate of user errors Subjective satisfaction –turnover rate Knowledge retention over time

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Design Principles Handle errors civilly. Allow easy reversal of actions. Use surprise effectively. Don’t lose the user.

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Keep It Simple Simple screen designs Minimal use of windows Screen density

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Error Checking Types Transaction Errors –field type (e.g., numeric) –field size –unreasonable quantity –field not filled in mandatory property / slot

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Error Checking (continued) Types (continued) –logical range (e.g., month) –negative balance –illogical combinations –record access not found duplicate

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Support Internal Locus of Control Minimize warnings No patronizing messages Avoidance of “we” or “I” User choices –color –screen placement –novice / experienced

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Easy Reversal of Actions Erase / undo Word / Line / Screen Escape menus Paging back

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Use Surprise Effectively Minimum highlighting Minimum input verification Few flashing or auditory signals

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Screen Structure Greeting Screen –Password Screen Main Menu –Intermediate Menus Function Screens –Form-filling –Transaction update

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Structure (Continued) Help screens (Pull Down) Escape options –Quit –Main Menu –Last screen

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Menus Option sequence –logical (new, update, delete) –frequency of choice –alphabetic Number options

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Interactive Structure GreetingScreenGreetingScreen MainMenuMainMenu IntermediateMenuIntermediateMenu FunctionScreenFunctionScreen PasswordScreenPasswordScreen IntermediateMenuIntermediateMenu FunctionScreenFunctionScreen IntermediateMenuIntermediateMenu FunctionScreenFunctionScreen Don’t Accept AcceptAccept Help Screens Escape Options (1)(1) (3)(3) (4)(4) (5)(5) (2)(2) (6)(6) (7) (4)(4)(4)(4) (5)(5) (5)(5)

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. 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 #)

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Common Screen Considerations Highlighting (< 10%) –color –reverse image –flashing –auditory Colors (don’t overdo)

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. 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 2004Sylnovie Merchant, Ph. D. 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

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Local Screen Density Mean clutter around each character How to reduce –minimize capital letters –limit punctuation –blank lines between text lines –minimize words used

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. 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

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Remember Entertainment is NOT system effectiveness!

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Prototyping

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Approaches Type I - Iterative –becomes final system Type II - Throwaway –used as model for final system

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Type I (Iterative) Life CycleRequirementsDefinitionRequirementsDefinitionPrototypeTrainingPrototypeTrainingProjectPlanningProjectPlanning RapidAnalysisRapidAnalysis DatabaseDesignDatabaseDesign DesignPrototypeDesignPrototype GeneratePrototypeGeneratePrototype TestPrototypeTestPrototype Acceptable?Acceptable? ImplementSystemImplementSystem MaintainSystemMaintainSystem NoNo YesYes

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Type II (Throwaway) Life CycleRequirementsDefinitionRequirementsDefinition AnalysisAnalysis DesignPrototypeDesignPrototype CodePrototypeCodePrototype TestPrototypeTestPrototype Acceptable?Acceptable? Code Final System System Test Final System System Acceptable?Acceptable? Implement Final System System Maintain Final System System YesYes NoNo NoNo YesYes

MIS 210 Fall 2004Sylnovie 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 2004Sylnovie 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 2004Sylnovie Merchant, Ph. D. Levels (Continued) Level 3 (Adaptive) –working model of system –system with training wheels –no bells or whistles

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. 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

MIS 210 Fall 2004Sylnovie Merchant, Ph. D. Disadvantages Poor documentation Hard to control/manage (Unrealistic) User expectations –time for final system –final system differences –reduced analysis