Systems Analysis and DFDs

Systems Life Cycle concept

Systems Analysis

Importance of Systems Analysis determines the CONTENT of an MIS represents 25% of the MIS development effort relates to performance higher budget compliance higher satisfaction

Data flow diagram (DFD)

Leveling DFDs How to factor a system? The BLACK BOX concept: you know the inputs it expects you know the outputs it should give back you know its function (what it does) you do not need to know the specifics to use it Controlling complexity of black boxes each box should solve one well-defined piece of the problem each box should be easy to understand connections should be made as simple as possible

Exploding DFDs

National Merchandising Case

Second level purchase order vendor account accounts payable accounts invoice check 1.0 2.0 3.0 due revise write Invoice Vendor vendor Vendor approval balance checks due payable invoices checking account

Third level

Third level - continued

Third level - end