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Analyze Structure Chart

Statement

  • Analyze and evaluate the following structure chart.

structure chart

  • Describe the morphology.
  • Is this diagram final or does it have problems?
  • If so, what are the problems and how would you fix them?

Solution

  • We evaluate the final structure chart for correctness, completeness, and consistency.
  • But before validating the above characteristics, we need to understand the morphology of the structure chart.
  • We evaluate the morphology of the structure according to different criteria(Conger, 2008):
    1. The depth.
    2. The width.
    3. The skew.
    4. The scope of effect.
    5. The coupling and cohesion.
  • We are going to discuss each of these criteria in its own section, providing some bullet points for each one.

Depth of modules

  • The depth of the structure chart is the number of levels in the hierarchy.
  • Too many levels = too much communication overhead and not enough real work is taking place.
  • In the provided chart, the depth of process8 and makeI is 2, while getG 3.
  • I believe there is big difference, and the depth of the chart looks good.

Width of modules

  • The width of a module is the number of processes that it contains or interacts with.
  • Process8 has 0, makeI has 2, and getG has 3.
  • Recommended width is 5-9 processes (Conger, 2008).
  • We notice the fan-out from getG to (getD, process4, process5); another fan-out from getD to (process1, process2, process3).
  • I believe the width of the chart looks good.

skew of modules

  • Skew measures the balance in the structure chart.
  • We can see the first branch to the left (getD) is longer, more dense than the other branches.
  • The chart is skewed to the left, indicating an input-bound application (input-skewed).
  • Possible solutions:
    • Depending on the implementation and the details of the application (that we can not tell from the chart), we can combine process1, process2, and process3 into getD.
    • Then, if possible, we can combine getD with process4, process5 into one process, or combine process5 with process6 into one process as process56
    • If the details of the application allows, we have balances the structure chart by following the two steps above.

Scope of effect

  • Scope of effect of a module is the number of processes that are conditionally processed based on a decision by the module.
  • Looking at the chart:
    • process8 has 0, makeI has 2, and getG has 3.
    • getD also has 3.
  • Ideal scope of effect is 0-1 (Conger, 2008).
  • So, getD, getG have a bad scope of effect that needs to be fixed.
  • By following the same steps that we used to fix the skew, we can fix the scope of effect.
  • combining processes 1,2 and 3 into getD, and process4,5 into getG we can really reduce the scope of effect and make the chart more balanced.

Coupling and cohesion

  • Coupling is a measure of the interdependence among different modules. Modules should be loosely coupled, or relatively independent (Chen & Tse, 2003).
  • Cohesion is a measure of the strength of association of elements within a module. It is recommended that elements should be highly cohesive, or strongly inter-related (Chen & Tse, 2003).
  • Coupling and cohesion are the two most important characteristics of a module.
  • Coupling and cohesion really depends on the domain knowledge of the application.
  • We can not really evaluate the coupling and cohesion of the chart without knowing the details of the application.

References