Chapter 10 Systems Planning, Analysis, and Design

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Chapter 10Systems Planning, Analysis, and Design
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Presentation Summary

1. The Steps of Systems Analysis
2. Fact-Gathering Techniques
3. Techniques for Organizing Facts
4. Structured Systems Analysis
5. The Steps of Systems Design

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I. The Steps of Systems Analysis

1. Survey the Present System
2. Identify Information Needs
3. Identify System Requirements
4. Develop a Systems Analysis Report

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A. Survey the Present System

• Four objectives of the system survey are
  concerned with
• Understanding the Operational Aspects of the
  Current System
• Establishing a Working Relationship with System
  Users
• Collection of Data for Systems Design
• Identification of Specific System Problems

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1. Understanding the Operational Aspects of the
Current System

• It is dangerous to try to modify an existing
  system that you do not thoroughly understand.
• The strengths and weaknesses of the current
  system must be identified before modifying the
  system.

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2. Establishing a Working Relationship with
System Users
The success or failure of a systems project
largely depends on the relationship between the
development team and the people who use the
system.

• Get to know the people involved in the system as
  soon as possible.
• Communicate the benefits of the new system.
• Provide assurance, when possible, of job security
  and no changes in job responsibilities.
• Project a genuine concern for making the life of
  the system user better.

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3. Collection of Data for Systems Design

• Internal data may be collected from sources like
  interviews, questionnaires, observations, and
  policy manuals.
• Outside data may be collected from industry
  publications, professional journals, and
  customers.

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4. Identification of Specific System Problems

• Effectiveness considers whether the system meets
  its objectives.
• Efficiency determines whether objectives are met
  at the lowest possible cost.
• Evaluation of the system should also consider
  bottlenecks. These are areas where small changes
  could result in major improvements.

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B. Identify Information Needs

• Identify the managers primary job responsibility.
• Identify the means by which the manager is
  evaluated.
• Identify some major problems the manager faces.
• Identify the way the manager evaluates personal
  output.

Managers often have difficulty in expressing just
how they make decisions. Identification of the
above areas can be helpful in pinpointing a
managers decision process. Identification of
problems may be best done by simply getting the
manager talking while you listen.
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C. Identify the System Requirements

• Requirements can be specified in terms of inputs
  and outputs.
• First determine the required outputs that a
  manager needs to make a decision.
• Then determine the inputs and processing needed
  to generate the outputs.

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D. The Systems Analysis Report
The report should organize and document the first
three phases of analysis. Some key elements of
the report include

• Description of the overall problems in subsystem
  being studied
• Recommendations for improving existing system or
  design of new system.
• Overall cost budget and timetable for project to
  date.

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II. Fact-Gathering Techniques

1. Fact Gathering Through Interviews
2. Fact Gathering Through Questionnaires

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A. Fact Gathering Through Interviews
1. Depth Interviews - Conversation is guided
largely by feelings and interest of the
person being interviewed.

1. Structured Interviews - Useful after a depth
   interview for obtaining answers to a specific set
   of questions.

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B. Fact Gathering Through Questionnaires
What types of information do you use to make
decisions?
1. Open-Ended Questionnaires - Persons provide
written answers to general rather than
specific questions.
2. Closed-End Questionnaires - Use for routine
situations or when a large number of
similar individuals would be questioned.
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III. Structured Systems Analysis

1. Structured Systems Analysis Defined
2. The Development of Logical Data Flow Diagrams
3. Defining Data Dictionaries
4. Defining Access Methods
5. Defining Process Logic

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A. Structured Systems Analysis Defined

• Structured systems analysis is a system of
  documentation.
• An approach to systems analysis that begins with
  a very general description of a particular
  system, and then moves to ever increasing detail
  ending with computer program code and other
  details.

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B. The Development of Logical Data Flow Diagrams

1. Data Flow Diagram Levels
2. Data Flow Diagram Symbols
3. Data Flow Diagram Conventions

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1. Data-Flow Diagram Levels
Context Diagrams represent the highest level of
data-flow diagrams. More detail is provided in
subsequent diagrams beginning at level zero.
Context Diagram
Stores
Requisition
0 Purchasing System
Purchase Details
Purchase File
Purchase Order
Vendors
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1. Data-Flow Diagram Levels
(Continued)
Stores
Requisition
1.0 Validate Requisition
Purchase Details
Purchase File
Details
2.0 Prepare Purchase Order
Purchase Order
Vendors
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2. Data-Flow Diagram Symbols

• Process symbol(s) in center of diagram identify
  system(s) under investigation.

• Sources and destinations of data and information
  are shown in rectangular symbols around the
  process symbol.

• Data flow lines describe the input data to the
  system and the output reports from the system.

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3. Data Flow Diagram Conventions

• Each process must have at least one input data
  flow and one output data flow.
• A data flow has at least one end connected to a
  process
• A diagram should not contain more than seven
  processes before being leveled into more detailed
  diagrams.

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C. Defining Data Dictionaries

• The data dictionary corresponds to the data
  stores referenced in the logical data flow
  diagrams. This involves giving a description of
  the data structure and data elements involved.

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D. Defining Access Methods

• It is necessary to specify how data stores will
  be accessed. This typically involves defining
  primary and secondary access keys. For example,
  in the purchase file the account-no-1 may serve
  as the primary key and person responsible as
  the secondary key.

Purchase File Description
Account Identifiers account-no-1
primary account
number account-no-2
secondary account number
person-responsible
person in charge of account Financial-Informat
ion account-balance
current balance last purchase
most
recent transaction
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E. Defining Process Logic

• There are a number of different approaches to
  documenting the process logic, including decision
  trees and structured English.
• Structured English is a special language for
  describing process logic that uses several key
  words, including IF, THEN, ELSE IF, and SO.
• Structured English does not include provisions
  for error conditions and data file access. If
  these are added, the resulting documentation is
  pseudocode. See pseudocode for a C program on
  the following slide.

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Pseudocode for A C Program
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V. Steps in Systems Design

1. Evaluation of Design Alternatives
2. Preparation of Detailed Design Specifications
3. Preparation of Systems Design Report

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A. Evaluation of Design Alternatives

• There are usually a number of attractive
  solutions that could be chosen.
• Completely new systems may be designed from
  scratch or a pre-made system could be
  recommended.
• Alternative systems should be documented with
  information concerning advantages/disadvantages
  and cost information.
• A given system must be feasible from both an
  operational and technical perspective.

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B. Preparation of Detailed Design Specifications
Reports and Other Outputs
1. Working with system objectives, the designer
should design all management reports and
operational output documents.
Database Design
Control Considerations
Specify Processing
2. Once all the outputs are specified, the data
inputs and processing steps are automatically
determined.
3. Once these decisions have been made, the
designer then builds in the appropriate controls.
Specify Inputs
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C. Preparation of Systems Design Report

• The completed design specifications should take
  the form of a proposal.
• Contents include timetables for completion, a
  budget, personnel requirements, and diagrams of
  the system to be implemented.

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Summary

• Four Steps of Systems Analysis
• Gathering Information Through Interviews and
  Questionnaires
• Structured Systems Analysis as a Form of
  Documentation
• Detailed Design Specifications