5.4 Process Model Quality Assurance

• Gathering information and organizing it in a process model is often done in a sequential way, and not simultaneously, there is a need for various steps of quality assurance.

Syntactic Quality and Verification

• Syntactic quality = Producing a process model that complies with the rules and guidelines.
  • Following the modeling language rules (ex. BPMN, no sequence flows across pools)
• Verification = Structural and behavioral correctness.
  • Structural correctness = Types of elements used and how they are connected.
    • ex. An activity should always have an incoming and outgoing arc.
  • Behavioral correctness = Relates to potential sequences of execution defined by the model.
    • ex. A case should never be able to reach a deadlock or a livelock.
    • Soundness = Common sound an unsound process fragments: See the picture above.

Semantic Quality and Validation

• Semantic quality = Goal of producing models that make true statements. about the considered domain, either for existing as-is processes or future to-be processes.
  • The model has to be compared with the real-world domain of a particular business process.
  • There are no formal rules to check semantic quality, it has to pass by the people involved in the process.
• Validation = Checking the semantic quality of a model by comparing it with the real-world business process.
  • Validity = All statements included in the model are correct and relevant to the problem.
    • A domain expert should point out any difference between what the model states and what is possible in reality.
    • Can be checked by simulations and interviews.
  • Completeness = The model contains all relevant statements on a process that would be correct.
    • Check if all the possible alternative processing options have been accounted for.

Pragmatic Quality and Certification

• Pragmatic Quality = Building a process model of good usability.
  • Predict how the model is going to be used.
  • Can be checked by how well a user understands the model.
• Certification = Checking the pragmatic quality of a process model by investigating its usage.
  • Aspects of usability:
    1. Understandability = How easy it is to read a specific process model.
       • Size of the model, structural complexity, graphical layout.
    2. Maintainability = The ease of applying changes to a process model.
    3. Learning = Relates to the degree of how good a process model reveals how a business process works in reality.
  • Certification can be conducted using user interviews or user experiments.
  • Improve usability by providing usability by applying design rules on the structure of the model.
  • Checks for Understandability, Maintainability and Learning:
    1. Consistency between the visual structure and logical structure.
    2. Using meaningful labels.

Modeling Guidelines and Conventions

• Modeling Guidelines and Conventions are an important tool to make sure the models are consistent and keep their integrity when multiple people are involved.
• Increase readability and compatibility.
• Using naming conventions, recommends the use of verb-object style for labeling of activities etc.
• Restrictions, for simplifying the set of elements used in BPMN.

• THE SEVEN MODELING GUIDELINES:
  1. Use as few elements in the model as possible. (Less elements == easier to understand)
  2. Minimize the routing paths per element. (Less paths == less chance to get errors)
  3. Use one start and one end event. (Less events == easier to understand)
  4. Model as structured as possible. (Better structured == easier to understand, less errors)
  5. Avoid OR-gateways. (No OR-gateways = easier to understand)
  6. Use verb-object activity labels. ( Less ambiguous == easier to understand)
  7. Decompose a model with more than 30 elements. (Less elements == easier to understand)