SAD-Fact Analysis

As data are collected, they must be organized and evaluated and conclusions drawn for preparing a report to the user for final review and approval. Some of the tools available for data organization and analysis are input/output analysis, decision tables, and structure charts.


Input/output analysis identifies the elements that are related to the inputs and output of a given system. Flow charts and data flow diagram are excellent tools for input/output analysis.


A flowchart, uses words to indicate a sequence of event. The words are enclosed in symbols linked by flow lines.

Example of flow chart: 

Initially the customer orders are received. Once orders are received, stock in the warehouse is verified. If the amount of stock available is sufficient for the delivery to the customer, then the order details are recorded. Batch orders are then prepared for a day. Any alterations in the orders are also noted. The data file is prepared accordingly. Once the date of delivery is confirmed a copy of the acknowledgement is sent to the head office, branch office, the sales representative, despatch and to the customer. Any pending orders are noted in the suspense file. If there are orders pending the whole process is repeated again else the process is ended. On the other hand if there is no sufficient stock, the information is passed on to the customer. If the customer sends a positive acknowledgement, the process continues else it ends.

Merits of a flowchart:
  •  They show logical interrelations clearly
  • They are easy to follow
  • They allow tracing of actions based on conditions

Demerits of flowchart:
  •  It is difficult to trace back from actions to the conditions
  •  Requirement to maintain a consistent level of detail to avoid confusion
Data flow Diagram:

Process modeling in detail is done using a data flow diagram. DFDs are used when there are very few constraints in developing or modifying the system under study. The DFDs consists of the following
  • Circles (or bubbles) that represents processes
  •  Rectangles that represent data stores
  •  Arrow that represents the data flow
  •  Squares represent providers (sources) or receivers (sinks) of data. 
Example for a data flow diagram: 

Incoming orders are checked for book titles, author’s names and other information and are batched with book orders from the same bookstore to determine the number of copies. Also the credit status of each store is checked before the shipment is authorized. Thus each shipment has a shipping notice giving the kind and the number of books shipped. This is compared with the original order to check for accuracy.


Decision tables describe the data flow within a system. They are generally used as a supplement when complex decision logic cannot be represented clearly in a flowchart

As a documenting tool, they provide a simpler form of data analysis than the flowchart. When completed, they are an easy to follow communication device between technical and nontechnical personnel.



A structure chart is a working tool and an excellent way to keep track of the data collected for a system. There are several variations of a structure chart. Initially the analyst starts with a single input/processing/output (IPO) chart, locates the module associated with the IPO on the hierarchy chart, and identifies the data elements along the line linking the module to a higher level.
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