level 1 dfd

This content is an extract from GetAhead in Business Analysis - the FULL course is in eBook and multimedia CD-Rom format.

Context & Level 1 dfd.
A level 1 dfd depicts the main functional areas of the system under investigation. It is derived with reference to the context diagram.
The context diagram on this screen depicts the overall business process for a generic system. Further analysis is then necessary in order to identify the major functional areas.

Identifying Level 1 Processes.
There is no formula that can be applied in deciding what is, and what is not, a level 1 process. Level 1 processes should describe only the main functional areas of the system, and you should avoid the temptation of including lower level processes on this diagram. As a general rule no business process diagram should contain more than 12 process boxes. The level 1 dfd is surrounded by the outline of a process box that represents the boundaries of the system. Because the level 1 diagram depicts the whole of the system under investigation, it can be difficult to know where to start. There are three different methods, which provide a practical way to start the analysis. These are explained in the following section and any one of them, or a combination, may prove to be the most helpful in any given investigation.

Three Start Points.
There are three different methods, which provide a practical way to start the analysis. These are explained in the following section and any one of them, or a combination, may prove to be the most helpful in any given investigation. The following illustrates each of these styles of diagram:
1) Resource flow analysis may be a useful method for starting the analysis if the current system consists largely of the flow of goods; as this approach concentrates on following the flow of physical objects.
2) The organizational structure approach starts from an analysis of the main roles that exist within the organization, rather than the goods or information that is flowing around the system.
3) The document flow analysis approach is appropriate if the part of the business under investigation consists principally of flows of information in the form of documents or computer input and output.

Resource Flow Analysis.
Resource flow analysis may be a useful method for developing diagrams if the current system consists largely of the flow of goods. This approach concentrates on following the flow of physical objects. Physical resources are traced from when they arrive within the boundaries of the system, through the points at which some action occurs, to their exit from the system. The rationale behind this method is that information will normally flow around the same paths as the physical objects. The resource flow diagram on this screen depicts the major vehicle movements as described in the ‘Roadhire Case Study’.

Organizational Structure Analysis.
The organizational structure approach starts from an analysis of the main roles that exist within the organization, rather than the goods or information that are flowing around the system. The organizational structure diagram for the ‘Roadhire Case Study’ is shown on this page. Let's suppose, for example, that the functions of the areas of the organization that are highlighted have been identified as being of interest to a specific investigation.

Using the organizational structure diagram in conjunction with the following case study extracts, two processes can be identified.
'Customers may make telephone or written bookings of vehicles to reception staff in local offices.'
'These are passed to the local booking staff who check against the local customer list to ...'
Have a think about the identification of these processes before you go to the next page.

Identification of these processes resulted from looking at the organizational structure and deciding which functional areas were relevant to the current investigation. By looking at these areas in more detail, using the case study text, discrete processes were then identified. Starting with these processes, the information flows between them and between these processes and external entities are then identified and added to the diagram.

This content is an extract from GetAhead in Business Analysis - the FULL course is in eBook and multimedia CD-Rom format. TOP