McLeod_CH07.ppt 4494KB Jan 27 2009 08:42:48 PM

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Management Information Systems, 10/e

Chapter 7

Learning Objectives

► Recognize the systems approach as the basic framework for solving problems of all kinds.

► Know how to apply the systems approach to solving systems problems.

► Understand that the systems development life cycle (SDLC) is a methodology – a recommended way to develop systems.

Learning Objectives (Cont’d)

► ► ► ► Be familiar with the main SDLC approaches – the traditional waterfall cycle, prototyping, rapid application development, phased development, and business process redesign.

Know the basics of modeling processes with data flow diagrams and use cases.

Understand how systems development projects are managed in a top-down fashion.

Be familiar with the basic processes of estimating project cost.

The Systems Approach

► ► ► John Dewey identified three series of judgments involved in adequately resolving a controversy 1.

Recognize the controversy 2.

Weigh alternative claims 3.

Form a judgment During the late 1960s/early 1970s, interest in systematic problem solving strengthened

Systems approach

— a series of problem-solving steps that ensure the problem is first understood, alternative solutions are considered, and the selected solution works.

Series of Steps

► Preparation effort prepares the problem solver by providing a systems orientation.

 Business areas, level of management, resource flows ► Definition effort consists of identifying the problem to be solved & then understanding it.

► Solution effort involves identifying alternative solutions, evaluating them, selecting the one that appears best, implementing that solution, & following up to ensure that the problem is solved.

Figure 7.1 Phases & Steps of Systems Approach

Figure 7.2 Each Business Area is a System

Definition Effort Terminology

► Problem trigger is a signal that things are going better or worse than planned.

► Symptom is a condition that is produced by the problem & is usually more obivious than the root cause of the problem.

► Problem is a condition or event that is harmful or potentially or beneficial or potentially beneficial to the firm.

Figure 7.3 Analyze System Parts in Sequence

Select the Best Solution

► Analysis – a systematic evaluation of options.

► Judgment – the mental process of a single manager.

► Bargaining – negotiations between several managers.

Systems Development Lifecycle

► ► ► Methodology is a recommended way of doing something.

Systems development lifecycle (SDLC) is an application of the systems approach to the development of an information system.

Traditional SDLC stages are:  Planning     Analysis Design Implementation Use.

Figure 7.4 Circular Pattern of the System Life Cycle

Prototyping

► Prototype is a version of a potential system that provides the developers & future users with an idea of how the system in its completed form will function.

► Prototyping is the process of producing a prototype.

► Best suited for small systems – reflecting the prototyping influence.

Evolutionary Prototype

► Evolutionary prototype is continually refined until it contains all of the functionality that users require of the new system. The steps involved are:  Identify user needs.

  Develop prototype.

► Integrated application developer ► Prototyping toolkit Determine if the prototype is acceptable.

 Use the prototype.

Figure 7.5 Development of Evolutionary Prototype

Requirements Prototype

► Requirements prototype is developed as a way to define the functional requirements of the new system when users are unable to articulate exactly what they want. Begin with the Evolutionary Prototype steps, then the next steps are:  Code the new system;  Test the new system;   Determine if the new system is acceptable; Put the new system into production.

Figure 7.6 Development of Requirements Prototype

Attraction of Prototyping

► ► ► ► ► Communications between the developer & user are improved.

The developer can do a better job of determining the users’ needs.

The user plays a more active role in system development.

The developers & the user spend less time & effort developing the system.

Implementation is much easier because the user knows what to expect.

Potential Pitfalls of Prototyping

► ► ► ► The haste to deliver the prototype may produce shortcuts in problem definition, alternative evaluation, & documentation. The shortcut produces a “quick & dirty” effort.

The user may get overly excited about the prototype, leading to unrealistic expectations regarding the production system.

Evolutionary prototypes may not be very efficient.

The computer-human interface provided by certain prototyping tools may not reflect good design techniques.

Rapid Application Development

► ► ► ► ► Rapid Application Development (RAD), is a term coined by James Martin. It refers to a development life cycle intended to produce systems quickly without sacrificing quality.

Information engineering is the name that Martin gives to his overall approach to system development, which treats it as a firm-wide activity.

Enterprise is used to describe the entire firm.

Essential to RAD is management, people, methodologies, & tools.

Best suited for large systems.

Figure 7.7 Rapid Application Development

Phased Development

► ► Phased development is an approach for developing information systems that consists of six stages:   Preliminary investigation Analysis   Design Preliminary construction   System test Installation.

Best suited for systems of all sizes.

Figure 7.8 Stages of Phases Development

Module Phases

► System is subdivided into major modules such as:    Report writer; Database; Web interface.

► Number of modules varies with the system from 1 to a dozen or so.

► Stages are performed separately for each module.

Figure 7.9 Module Phase of Systems Development

Business Process Redesign

► ► ► Reengineering or Business process redesign (BPR) is the process of reworking the systems.

 Systems include both those that process the firm’s data & those that perform basic functions such as drilling for oil.

BPR affects the firm’s IT operations in two ways:  Aids in the redesign of old information systems ( systems); legacy  Applies to the redesign of information systems to support major operations.

Usually initiated at strategic management level.

Figure 7.10 Top-Down Initiation of BPR Projects

Strategic Initiation of BPR

► ► ► ► Reverse engineering is the process of analyzing an existing system to:  identify its elements & their interrelationships;  Create documentation at a higher level of abstraction than currently exists.

Functionality is the job that it performs.

Reengineering is the complete redesign of a system with the objective of changing its functionality.

Forward engineering is given to the process of following the SDLC in the normal manner while engaging in BPR.

BPR Components

► BPR components can be applied separately or in combination.

► Functional quality is a measure of what the system does.

► Technical quality is a measure of how well it does it.

Figure 7.11 BPR Component Selection

Methodologies in Perspective

► Traditional SDLC is an application of the systems approach to the problem of system development; contains all elements.

► Prototyping is an abbrev. form focusing on the definition & satisfaction of user needs.

► RAD is an alternative approach to the design & implementation phases of SDLC.

System Development Tools

► Process modeling  ISO standards  was first done with Use of 20+ symbols flowcharts .

► Data flow diagrams (DFD) is a graphic representation of a system that uses four symbol shapes to illustrate how data flows through interconnected processes..

► DFDs are excellent for modeling processes at a summary level.

Data Flow Diagram Symbols

► ► ► ► ► Terminator describes an environmental element, such as a person, organization, or another system.

 Environmental elements exist outside the boundary of the system.

Process is something than transforms input into output.

Data flow consists of a group of logically related data elements that travel from one point or process to another; can diverge and converge .

Data storage is a repository of data.

Connector contains the number of the process that provides the data flow.

Figure 7.12 DFD of a Sales Commission System

Leveled Data Flow Diagrams

► ► ► ► Leveled DFDs is used to describe the hierarchy of diagrams, ranging from context to lowest-level n diagram. Figure 0 diagram identifies the major processes of a system.

 Use additional DFDs to achieve documentation at both a more summarized & a more detailed level.

Context diagram is a diagram that documents the system at a more summarized level.

 Positions the system in a environmental context.

Figure n

 n diagram is a diagram that provides more detail.

represents the # of processes on the next higher level.

 Documents a single process of a DFD in greater detail.

Figure 7.13 Context Diagram of a Sales Commission System

Figure 7.14 Figure 4 Diagram of a Sales Commission System

Use Cases

► ► ► ► Use case is a narrative description in an outline form of the dialog that occurs between a primary & secondary system.

Continuous narrative format with each action numbered sequentially.

Ping-pong format consists of two narratives & the numbering indicates how the tasks alternate between the primary & secondary systems.

Alternative events are actions that are not normally expected to occur; alphabetic letters are appended to step numbers.

Figure 7.15 A Use Case

Figure 7.16 Use Case Guidelines

Project Management

► Steering committee is a committee with the purpose of providing ongoing guidance, direction, & control of all systems projects.

► MIS steering committee purpose is directing the use of the firm’s computing resources.

   It establishes policies.

It provides fiscal control.

It resolves conflict.

Figure 7.17 Managers of a System Life Cycle Arranged in a Hierarchy

Project Leadership

► Project team includes all of the persons who participate in the development of an information system.

► Team leader (project leader) provides direction throughout the life of the project.

Project Management Mechanism

► ► ► ► Basis for project management is the project plan.

Gantt chart is a horizontal bar chart that includes a bar for each task to be performed; bars arranged in time sequence.

Network diagram (

CPM diagram, PERT chart

) is a drawing that identifies activities & links them with arrows to show the sequence in which they are to be performed.

Narrative reports are in the form of weekly written reports by project leader, communicates project information to MIS steering committee.

Figure 7.18 A Gantt Chart

Figure 7.19 A Network Diagram

Project Cost-Estimating

► ► ► Cost-estimating inputs     Work breakdown structure (WBS) Resource requirements, resource rates Activity duration estimates Historical information Cost-estimating tools & techniques    Bottom-up estimating Computerized estimating Mathematical models Cost-estimating outputs   Supporting details Cost-management plan © 2007 by Prentice Hall Management Information Systems, 10/e Raymond McLeod and George Schell 48