Data Flow Diagram

A Data Flow Diagram (DFD) is used to graphically represent the "flow" of data through an information system, modeling its process aspects. 

Why:

  • A DFD helps to document the logical stages through which your data travel;
  • A DFD describes how data are collected, transmitted, processed, stored and displayed;
  • A DFD provides a plan for data processing implementation;
  • To describe an existing data process as a way of increasing understanding of the process details.

How:

  • A DFD is usually developed by starting with a general model of data flow;
  • Subsequently refine the DFD into successively detailed models;
  • A DFD is updated continually so long as a data process exists to account for changes.
Notes:
It is important to adopt a standard notation for one's diagram. DFDs are generally produced with a graphics program such as Microsoft Visio.

Example:

The Alaska Region uses data flow diagrams to document its Catch-In-Areas (CIA) database, a GIS-based analysis tool for catch data. CIA is used to analyze fisheries closures and definitions. The DFD documentation has allowed the team that maintains the CIA system to expand to meet the database's expanding use.

Click here for the data flow diagram from this case study.

Subject Ambassadors:

Ed Hoch - Alaska Region Office: edward.hoch@noaa.gov

Jeff Cowen - Northwest Fisheries Science Center: jeff.cowen@noaa.gov

Steve Lewis - Alaska Region Office: steve.lewis@noaa.gov