Back to Process Modeling and Analysis

Data Flow Diagrams (DFD)

5 minutes 5 Questions

Data Flow Diagrams (DFDs) are a traditional technique used in systems analysis to represent the flow of data within a system. They provide a graphical illustration of how data moves through processes, where it is stored, and how it interacts with external entities. DFDs focus on the data and the transformations that occur as data moves from input to output, rather than the steps or sequence of operations. This makes DFDs particularly useful for understanding the logical flow of information and identifying where data inputs come from, how they are processed, and where the results go. A DFD typically consists of four main components: processes, data stores, data flows, and external entities. Processes represent functions or activities that transform data; data stores are repositories where data is held; data flows are the pipelines through which data moves; and external entities are outside systems or actors that interact with the system. By mapping these components, analysts can visualize how data circulates within the system and identify potential issues such as data redundancy, bottlenecks, or security vulnerabilities. In process modeling and analysis, DFDs are instrumental in decomposing complex systems into more manageable sub-systems. They enable analysts to break down high-level functions into detailed processes, facilitating a deeper understanding of the system’s functionality. DFDs also support communication between technical and non-technical stakeholders by providing a clear and shared representation of the system's data flows. This can aid in requirement gathering, system design, and validation processes. Additionally, DFDs can be used to analyze the impact of changes within the system, ensuring that any modifications enhance system performance without introducing new issues. Overall, Data Flow Diagrams are a fundamental tool for modeling data-centric processes and supporting system analysis and design.

Test mode:
Start practice test
PMI-PBA - Process Modeling and Analysis Example Questions

Test your knowledge of Amazon Simple Storage Service (S3)

Question 1

What is the significance of double lines used to represent a data store in a Data Flow Diagram (DFD)?

Correct Answer: It indicates a file that exists physically

In Data Flow Diagrams (DFDs), double lines used to represent a data store signify a physical file or storage that exists in the system. This is a fundamental concept in DFD notation, where the double parallel lines indicate permanent data storage that persists over time and maintains data between processes. The other options are incorrect because: - Having online and offline modes is not represented by double lines in DFDs - Temporary data stores are not indicated by double lines - in fact, permanent storage is what double lines represent - Redundant storage systems with multiple copies are not depicted by double lines in DFD notation Double lines in DFDs specifically represent the physical existence of data storage, which could be files, databases, or other forms of persistent storage, making this the standard notation in DFD modeling.

Question 2

In a Data Flow Diagram (DFD), what characteristic of an external entity makes it unique from other symbols?

Correct Answer: It represents a source or destination outside the system boundary

In a Data Flow Diagram (DFD), an external entity is distinct because it represents sources or destinations that exist outside the system's boundaries. These entities interact with the system by providing inputs or receiving outputs, but they are not part of the system itself. The other options are incorrect because: A collection of data elements flowing through processes describes data flows, not external entities. The movement and processing of data between components describes the overall purpose of a DFD, not a specific characteristic of external entities. Data storage locations (temporary and permanent) are represented by different symbols in DFDs and serve a different purpose than external entities.

Question 3

In a Data Flow Diagram (DFD), what technique should be applied when decomposing processes from level 0 to level 1?

Correct Answer: Child processes must total to their parent process

The fundamental principle of process decomposition in Data Flow Diagrams (DFD) is that child processes must sum up to represent their parent process completely. This balancing rule is essential for maintaining the integrity and consistency of the DFD. This means that when a process is broken down into its subprocesses (children), these subprocesses must collectively represent all the functionality of the parent process - no more and no less. The other answers are incorrect because: - Having three data flows from the parent diagram is an arbitrary rule that has no basis in DFD methodology - There is no requirement for data flows to match the count of external entities - The number of data stores between parent and child levels can vary based on the actual needs of the process being modeled The correct principle ensures that the decomposition maintains functional equivalence across different levels of the DFD, preserving the logical integrity of the system being modeled.

Go Premium

PMI Professional in Business Analysis Preparation Package (2024)

  • 3015 Superior-grade PMI Professional in Business Analysis practice questions.
  • Accelerated Mastery: Deep dive into critical topics to fast-track your mastery.
  • Unlock Effortless PMI-PBA preparation: 5 full exams.
  • 100% Satisfaction Guaranteed: Full refund with no questions if unsatisfied.
  • Bonus: If you upgrade now you get upgraded access to all courses
  • Risk-Free Decision: Start with a 7-day free trial - get premium features at no cost!
More Data Flow Diagrams (DFD) questions
13 questions (total)
Start 13 question test