Download Systems & Systems Analysis

Systems & Systems Analysis
Yale Braunstein
School of Information Management & Systems
UC Berkeley
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Working Definition of “System”
 A system is a network of inter-related
procedures joined together to perform an
activity or accomplish an objective
 (Note that the level of technology is NOT
specified—there are low-tech systems as well as
high tech systems)
 (Also note that the “breadth” of the system is
not specified. More on this later.)
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So, what is a “procedure” ?
 A procedure is the precise series of instructions
that that explain:
 What is to be done
 Who will do it
 When it will be done
 How …
 (Note the parallels to programming
terminology)
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Types of Systems
 Open system: does not provide for its own
control
 Closed system: automatically controls or
modifies it own operations
A recurring thought: It is important to look
at how the system handles exceptions.
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Functions of the Systems Analyst
1.
Forms design & control
2.
Procedure writing & procedure manual
control
3.
Records management
4.
Report control
5.
Office & workplace layout
6.
Work simplification studies
(This is not an exhaustive list.)
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SYSTEM DEVELOPMENT
METHODOLOGIES
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What Is a Methodology?
 A formalized approach or series of steps
 Examples



Process-Centered
Data-Centered
Object-Oriented
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Waterfall Development Method
Evaluation!
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More detail
1.
Define problem
2.
Outline system study
3.
Obtain background information & understand
interactions
4.
Understand existing “system”
5.
Define system requirements
6.
Design new system / generate alternatives
7.
Design system controls
8.
Prepare cost comparisons
9.
Sell system to management
10. Provide for implementation, follow-up, evaluation
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Pros and Cons of the Waterfall Method
Pros
Identifies systems
requirements long
before programming
begins
Cons
Design must be
specified on paper
before programming
begins
Long time between
system proposal and
delivery of new
system
[Digression on “internet time” goes here.]
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Alternatives to the SDLC*
 Parallel Development
 Rapid Application Development (RAD)
 Phased Development
 Prototyping
 Spiral Development
 Packaged Systems
*Systems development life cycle
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Parallel Development Method
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Pros and Cons of Parallel Development
Pros
Cons
Reduces Scheduled
Time
Still Uses Paper
Documents
Less Chance of
Rework
Sub-projects May Be
Difficult to Integrate
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Rapid Application Development
 CASE tools
 JAD sessions
 Fourth generation/visualization programming
languages
 Code generators
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Three RAD Categories
 Phased development

A series of versions
 Prototyping

System prototyping
 Throw-away prototyping

Design prototyping
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How Prototyping Works
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Throwaway Prototyping
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Criteria for Selecting the Appropriate
Methodology
 Clear user requirements
 Familiar technology
 Complexity
 Reliability
 Time schedule
 Schedule visibility
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How broad should the analysis be?
What is the system being studied?
 Look at one or more of five levels:
1.
2.
3.
4.
5.
Entire firm, organization
One division
Departmental interaction
Functional areas within a department
A specific problem area within a
function
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The “sub-optimization” problem
 Sub-optimal: what is best from the narrow
point-of-view may not be best when other
functions, divisions, etc., are taken into
consideration.
 Similar to “externalities” in economics
 Examples:
–Freight & passenger service using same
routes
–Internal & external networks
–Carriers & content providers
 “Sub-optimal” is different from “non-optimal”
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“Black-box” models
OUTPUTS
INPUTS
External
Environment
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Sources
 Text, Chapter 1
 “History of Project Management”
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