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First off, let's start with defining what a data flow diagram is in the first place. A data flow diagram is a graphical representation of data flow in a process or information system. These diagrams can become and invaluable asset in your presentation if used properly.

Usually this technique starts with a very high level graphical representation showing and overall picture of the business and processes and continues down to the lower levels of the process through the presentation. This is often called top-down expansion. By presenting this analysis, the audience can literally walk with you through the process and see each discrete point as you lead them through the presentation. This is especially useful with business stakeholders who have a stake in the work flow or process you are discussing. Often times, they may not have ever seen the high level view of the given process or flow.

To get started, simply start with a context diagram. This is usually a simple representation of the entire system, process, or data flow your are discussing. Next, follow up with a level 1 flow diagram; which provides an overview of the major functional areas of the business. At this point, don*t get into the details. Keep the level 1 diagram at a high level and start addressing all the areas of interest that your audience has a stake in. Make sure you are using terminology that makes sense to them. The easiest way to lose your audience is to use acronyms or terminology that they cannot relate to.

Now that you have your level 1 diagram, you are ready to create the level 2 business flow diagram. Continue to peal the layers of the process back in your presentation going deeper at each level. Typically, you will want to keep it no more than four (4) layers deep. Any deeper and you will lose your audience for sure. A good approach is provide hand outs that the attendees can take with them.

Identifying the existing business processes, using a technique like data flow diagrams, is an essential step to business process re-engineering, migration to new technology, or improving any work flow related to your business.

Here are a few pieces you will need in your flow diagram:

External Entity

An external entity is a source or destination of a data flow which is outside of your process. This could be anything where data originates outside of your process. The symbol used is an oval containing a meaningful and unique identifier.

Process

A process shows a transformation or manipulation of data flows within your system. The symbol used is a rectangular box which usually contains three elements. The first is a number that appears in the upper left hand corner.1

Firstly an identification number appears in the upper left hand corner. This is allocated arbitrarily at the top level and serves as a reference. Second, you must put a identifier that describes where in the system the process takes place. An example is a piece of hardware, or department. Finally, a descriptive title is placed in the centre of the box. This should be a simple statement with a specific verb, for example 'maintain vendor records' or 'find need'.

Data Flow

A data flow shows the flow of information from its source to its destination. A data flow is represented by a line, with arrowheads showing the direction of flow.

Data Store

A data store is a holding place for information within the system: It is represented by an open ended narrow rectangle. An example might be a batch of invoices or a queue in a system that stores records before processing.

Resource Flow

A resource flow shows the flow of any physical material from its source to its destination.

The physical resource needs to be identified and labelled.

Now you are set to create an informative and compelling presentation.