systems analysis & design 7 th edition chapter 7

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Systems Analysis & Design 7 th Edition Chapter 7

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Page 1: Systems Analysis & Design 7 th Edition Chapter 7

Systems Analysis & Design

7th Edition

Chapter 7

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Phase Description

Systems Design is the third of five phases in the systems development life cycle (SDLC)

Now you are ready to begin the physical design of the system that will meet the specifications described in the system requirements document

Systems design tasks include output and user interface design, data design, and system architecture

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Chapter Objectives

Discuss output design issues and various types of output

Design various types of reports, and suggest output controls and security

Explain the concept of user interface design and human-computer interaction, including the basic principles of user-centered design

List specific guidelines for user interface design

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Chapter Objectives

Describe user interface techniques, including screen elements and controls

Explain input design concepts, techniques, and methods

Describe guidelines for data entry screen design

Use validation checks for reducing input errors

Design effective source documents and input controls

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Introduction

Output and user interface design is the first task in the systems design phase of the SDLC

Output design focuses on user needs for screen and printed forms of output, while user interface design stresses user interaction with the computer, including input design and procedures

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Output Design

Before designing output, ask yourself several questions:

– What is the purpose of the output?

– Who wants the information, why it is it needed, and how will it be used?

– What specific information will be included?

– Will the output be printed, viewed on-screen, or both? What type of device will the output go to?

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Output Design

Types of Output

– In the systems design phase, you will create the actual forms, reports, documents, and other types of output

– Internet-based information delivery

– E-mail

– Instant Messaging

– Wireless Devices

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Output Design

Types of Output– Digital audio, images, and video– Podcasts– Automated facsimile systems

• Faxback systems (request fax using email or website

– Computer output microfilm (COM)– Computer output to digital media

• Used when many documents must be scanned, stored in digital format)

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Output Design

Types of Output– Specialized Forms of Output

• An incredibly diverse marketplace requires a variety of specialized output

– Output from one system often becomes input into another system

– Although digital technology has opened new horizons in business communications, printed output still is the most common type of output, and specific considerations apply to it

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Printed and Screen Output

Reports

– Detail reports

–Detail reports

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Printed and Screen Output

Reports

– Exception reports• Are useful when the user wants information only

on records that might require action

– Summary reports• Reports used by individuals at higher levels in

the organization include less detail than reports used by lower-level employees

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Printed and Screen Output

– Exception report

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Printed and Screen Output

– Summery report

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Printed and Screen Output

User Involvement in Report Design

– Printed reports are an important way of delivering information to users, so recipients should approve all report designs in advance

– To avoid problems submit each design for approval as you complete it, rather than waiting until you finish all report designs

– Mock-up• Sample report or prototype for users to review

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Printed and Screen Output

Report Design Principles

– Printed reports must be attractive, professional, and easy to read

– Report headers and footers

– Page headers and footers

– Column heading alignment

– Column spacing

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Printed and Screen Output

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Printed and Screen Output

Report Design Principles

– Field order• Fields should be displayed and grouped in a

logical order

– Grouping detail lines• It is meaningful to arrange detail lines in groups

• Group header

• Group footer

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Printed and Screen Output

Report Design Issues

– Good design standards produce reports that are uniform and consistent

– When a system produces multiple reports, each report should share common design elements

– After a report design is approved, you should document the design in a report analysis form

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Printed and Screen Output

Designing Character-Based Reports

– Many systems still produce one or more character-based reports

– When report designers create or modify a character-based report, they use a traditional tool that still works well, called a printer spacing chart

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Printed and Screen Output

Printing Volume and Time Requirements

– Length calculations

– Time calculations• Ppm (pages per minute)

• Line printers often use greenbar paper

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Printed and Screen Output

Output Control and Security

– Output must be accurate, complete, current, and secure

– The IT department is responsible for output control and security measures

– Many companies have installed diskless workstations

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User Interface Design

Evolution of the User Interface– Process-control– User-centered

system

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User Interface Design

Human-Computer Interaction

– Human-computer interaction (HCI) describes the relationship between computers and people who use them to perform business-related tasks

– Main objective is to create a user-friendly design that is easy to learn and use

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User Interface Design

Human-Computer Interaction

– User rights cited by Dr. Karat include• Perspective

• Installation

• Compliance

• Instruction

• Control

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User Interface Design

Human-Computer Interaction

– User rights cited by Dr. Karat include• Feedback

• Dependencies

• Scope

• Assistance

• Usability

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User Interface Design

Basic Principles of User-Centered Design

– Understand the underlying business functions

– Maximize graphical effectiveness

– Profile the system’s users

– Think like a user

– Use prototyping

– Storyboard

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User Interface Design

Basic Principles of User-Centered Design

– Usability metrics

– Design a comprehensive interface

– Continue the feedback process

– Document the interface design

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User Interface Design

Guidelines for User Interface Design

– Follow eight basic guidelines1. Focus on basic objectives

2. Build an interface that is easy to learn and use

3. Provide features that promote efficiency

4. Make it easy for users to obtain help or correct errors

5. Minimize input data problems

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User Interface Design

Guidelines for User Interface Design

– Follow eight basic guidelines6. Provide feedback to users

7. Create an attractive layout and design

8. Use familiar terms and images

– Good user interface design is based on a combination of ergonomics, aesthetics, and interface technology

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User Interface Design

Guidelines for User Interface Design

– Focus on basic objectives

– Build an interface that is easy to learn and use

– Provide features that promote efficiency

– Make it easy for users to obtain help or correct errors

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User Interface Design

Guidelines for User Interface Design

– Minimize input data problems

– Provide feedback to users

– Create an attractive layout and design– Use familiar terms and images

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User Interface Design

User Interface Controls

– Menu bar

– Toolbar

– Command button

– Dialog box

– Text box

– Toggle button

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User Interface Design

User Interface Controls

– List box – scroll bar

– Drop-down list box

– Option button, or radio button

– Check box

– Calendar control

– Switchboard

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Input Design

Input technology has changed dramatically in recent years

The quality of the output is only as good as the quality of the input

– Garbage in, garbage out (GIGO)

– Data capture

– Data entry

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Input Design

Input and Data Entry Methods

– Batch input• Batch

– Online input• Online data entry

• Source data automation

• RFID tags or Magnetic data strips

• POS, ATMs

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Input Design

Input and Data Entry Methods

– Tradeoffs• Unless source data automation is used, manual

data entry is slower and more expensive than batch input because it is performed at the time the transaction occurs and often done when computer demand is at its highest

• The decision to use batch or online input depends on business requirements

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Input Design

Input Volume

– Guidelines will help reduce input volume1. Input necessary data only

2. Do not input data that the user can retrieve from system files or calculate from other data

3. Do not input constant data

4. Use codes

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Input Design

Designing Data Entry Screens

– Most effective method of online data entry is form filling

– Guidelines will help you design data entry screens1. Restrict user access to screen locations where

data is entered

2. Provide a descriptive caption for ever field, and show the user where to enter the data and the required or maximum field size

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Input Design

Designing Data Entry Screens

– Guidelines will help you design data entry screens3. Display a sample format if a user must enter

values in a field in a specific format - separator

4. Require an ending keystroke for every field

5. Do not require users to type leading zeroes for numeric fields

6. Do not require users to type trailing zeroes for numbers that include decimals

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Input Design

Designing Data Entry Screens– Guidelines will help you design data entry

screens7. Display default values so operators can press the

ENTER key to accept the suggested value8. Use a default value when a field value will be

constant for successive records or throughout the data entry session

9. Display a list of acceptable values for fields, and provide meaningful error messages

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Input Design

Designing Data Entry Screens– Guidelines will help you design data entry

screens10. Provide a way to leave the data entry screen at

any time without entering the current record11. Provide users with an opportunity to confirm

the accuracy of input data before entering it12. Provide a means for users to move among

fields on the form

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Input Design

Designing Data Entry Screens

– Guidelines will help you design data entry screens13. Design the screen form layout to match the

layout of the source document

14. Allow users to add, change, delete, and view records

15. Provide a method to allow users to search for specific information

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Input Design

Input Errors

– Reducing the number of input errors improves data quality

– A data validation check improves input quality by testing the data and rejecting any entry that fails to meet specified conditions

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Input Design

Input Errors

– At least eight types of data validation checks1. Sequence check

2. Existence check

3. Data type check

4. Range check – limit check

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Input Design

Input Errors

– At least eight types of data validation checks5. Reasonableness check

6. Validity check – referential integrity

7. Combination check

8. Batch controls – hash totals

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Input Design

Source Documents

– Form layout

– Heading zone

– Control zone

– Instruction zone

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Input Design

Source Documents

– Body zone

– Totals zone

– Authorization zone

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Input Design

Source Documents

– Information should flow on a form from left to right and top to bottom to match the way users read documents naturally

– A major challenge of Web-based form design is that most people read and interact differently with on-screen information compared to paper forms

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Input Design

Source Documents

– Dr. Jakob Nielson believes that users scan a page, picking out individual words and sentences

– As a result, Web designers must use scannable text to capture and hold a user’s attention

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Input Design

Input Control

– Every piece of information should be traceable back to the input data

– Audit trail

– Data security

– Records retention policy

– Encrypted – encryption

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Chapter Summary

The chapter began with a discussion of output design issues and a description of various types of output

User-centered design principles require an analyst to understand the business functions, maximize graphical effectiveness, profile the system’s users, think like a user, use prototyping, design a comprehensive interface, continue the feedback process, and document the interface design

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Chapter Summary

An effective way to reduce input errors is to reduce input volume

You can also reduce errors by using well-designed data entry screens and by using data validation checks

Chapter 7 complete