Tag: Cause Effect Graph

Cause Effect Graph Technique | Examples

Cause Effect Graph-


  • Cause Effect Graph is a popular black box testing technique.
  • It illustrates the relationship between a given outcome and all the factors that influence the outcome graphically.




  • A “Cause” stands for a distinct input condition that fetches about an internal change in the system.
  • An “Effect” represents an output condition, a system state that results from a combination of causes.




  • For analyzing the existing problem so that corrective actions can be taken at the earliest.
  • For relating the interactions of the system with the factors affecting a particular process.
  • For identifying the possible root causes, reasons for a particular effect, problem or outcome.




  • It helps to determine the root causes of a problem or quality.
  • It indicates possible causes of variation in a process.
  • It identifies those areas where data should be collected for further study.
  • It utilizes the team knowledge of the process by encouraging team participation.


Steps For Drawing Cause Effect Diagram-


The following steps are followed-

  • Identify and describe the input conditions (causes) and actions (effect).
  • Build up a cause-effect graph.
  • Convert cause-effect graph into a decision table.
  • Convert decision table rules to test cases where each column of the decision table represents a test case.






Design test cases for the following problem-

If the character of the first column is ‘A’ or ‘B’ and the second column is a number, then the file is considered updated. If the first character is erroneous, then message x should be printed. If the second column is not a number, then message y should be printed.






Identify and describe the input conditions (causes) and actions (effect).


The causes represented by letter “C” are as follows-

  • C1 : The character in column 1 is ‘A’
  • C2 : The character in column 1 is ‘B’
  • C3 : The character in column 2 is a number


The effects represented by letter “e” are as follows-

  • e1 : File update is made
  • e2 : Message x is printed
  • e3 : Message y is printed




Build up a cause-effect graph-





Convert cause-effect graph into a decision table-


Test data Causes Effect
A1 A2 A3 M1 M2 M3
1 0 0 0 0 1 1
2 0 0 1 0 1 0
3 0 1 0 0 0 1
4 0 1 1 1 0 0
5 1 0 0 0 0 1
6 1 0 1 1 0 0




Why Cause Effect Graphing Technique is Better Than Any Other Black Box Testing Technique?




  • Boundary value analysis and equivalence partitioning do not explore combinations of input circumstances.
  • These only consider the single input conditions.
  • However, combinations of inputs may result in interesting situations.
  • These situations should be tested.
  • By considering all the valid combinations of equivalence classes, there will be large number of test cases.
  • Many of these test cases will not be useful for revealing any new errors.


On the other hand,

  • Cause Effect Graph is a technique that helps in selecting a high-yield set of test cases in a systematic way.
  • It has a beneficial effect in pointing out incompleteness and ambiguities in the specifications.


To gain better understanding about Cause Effect Graph Technique,

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