Systems & Systems Analysis

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					Systems & Systems Analysis

            Yale Braunstein
School of Information Management & Systems
                UC Berkeley



                                             1
  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.)


                                              2
      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)

                                               3
            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.


                                             4
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.)
                                            5
SYSTEM DEVELOPMENT
  METHODOLOGIES




                     6
         What Is a Methodology?

 A formalized approach or series of steps

 Examples
     Process-Centered
     Data-Centered
     Object-Oriented




                                             7
Waterfall Development Method




                         Evaluation!




                             8
                  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
                                                  9
Pros and Cons of the Waterfall Method

              Pros                 Cons

                             Design must be
                             specified on paper
        Identifies systems
                             before programming
        requirements long
                             begins
        before programming
        begins
                             Long time between
                             system proposal and
                             delivery of new
                             system


     [Digression on “internet time” goes here.]
                                                   10
      Alternatives to the SDLC*

 Parallel Development

 Rapid Application Development (RAD)

 Phased Development

 Prototyping

 Spiral Development

 Packaged Systems

        *Systems development life cycle
                                          11
Parallel Development Method




                              12
Pros and Cons of Parallel Development


             Pros                 Cons


        Reduces Scheduled      Still Uses Paper
              Time               Documents


          Less Chance of    Sub-projects May Be
             Rework         Difficult to Integrate




                                                     13
 Rapid Application Development

 CASE tools

 JAD sessions

 Fourth generation/visualization programming
 languages
 Code generators




                                         14
Three RAD Categories

  Phased development
      A series of versions
  Prototyping
      System prototyping
  Throw-away prototyping
      Design prototyping



                              15
How Prototyping Works




                        16
Throwaway Prototyping




                        17
Criteria for Selecting the Appropriate
             Methodology
          Clear user requirements

          Familiar technology

          Complexity

          Reliability

          Time schedule

          Schedule visibility


                                     18
How broad should the analysis be?
What is the system being studied?
 Look at one or more of five levels:
  1.   Entire firm, organization
  2.   One division
  3.   Departmental interaction
  4.   Functional areas within a department
  5.   A specific problem area within a
       function

                                        19
 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”

                                              20
  “Black-box” models


INPUTS                 OUTPUTS




           External
         Environment

                                 21
            Sources

 Text, Chapter 1

 “History of Project Management”




                                    22

				
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