KK: How to Get Started Drawing a Detailed Data Flow Diagram (DFD)

Finding Lower-Level Processes as a Crucial First Step toward Creating a Detailed Dataflow Diagram


Author: Tom and Angela Hathaway
Video Duration: 13:31 minutes

This KnowledgeKnugget™ is part of an eBook and an eCourse

Video Overview

In this KnowledgeKnugget™ you will learn step 1 in how to explode a Dataflow Diagram. Looking inside a complex process on a Dataflow Diagram can reveal hidden data and uncover potential problem areas. The first step toward ultimately exploding or leveling a process is to identify the internal processes that will become visible on a more detailed Dataflow Diagram.

Video Transcript Excerpt

How to Identify Internal Processes for a Data Flow Diagram

Hello, I’m Tom Hathaway. I’m wearing my BA hat to symbolize that anyone in an organization might do business analysis, whether or not they have the job title "Business Analyst", so let’s talk business analysis. This KnowledgeKnugget™ introduces the concept of leveling or exploding processes on a Data Flow Diagram, explains why it is important, and how to analyze interview notes to reveal lower-level processes in preparation to leveling the diagram. This simple technique will help you when you are the one wearing the BA hat.

One of the simplest tools for visualizing project scope is a Context-level Data Flow Diagram (DFD). Beyond making the project scope visible, the DFD gives you the ability to discover, analyze, and represent functional and non-functional requirements. However, as revealing and useful as the Context Diagram may be, it is certainly lacking a lot of detail. In Data Flow Diagramming lingo, detail is revealed by "exploding" or "leveling" complex processes to identify internal processes and flows that are not visible at the higher level. By exploding a process, you will also identify internal data stores, meaning places where the data just sits within the process waiting until it is used by another process. Delving into this level of detail may also allow you to discover additional missing data and processes.

Each of the internal processes creates and consumes specific data. If you draw a data flow diagram at this more detailed level, you uncover internal data flows and data stores that are more specific and detailed as well. Any process at any level of detail is a potential candidate for exploding. The only factor to consider is whether you understand the process sufficiently to predict how change will affect it.

Data Flow Diagramming Case Study

For our working example we are going to use the ENTER ORDERS Context Level DFD that we created based on interview notes from Mary, the project sponsor. At the context level, I only have one process, namely ENTER ORDERS. To understand that process at the appropriate level of detail, I need details, meaning I am going to look inside the ENTER ORDERS process and define how it currently works in Mary’s organization.

You may want to pause the video to familiarize yourself with the context-level diagram and the interview notes at this time.

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