# Part III System Analysis and Design; Programming - PowerPoint PPT Presentation

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Part III System Analysis and Design; Programming. Decision Support Systems Pictorial Model Tools: Excel, VBA, IFPS *. Decision Support Systems (1.2). Supports Decisions Must identify decision criteria (e.g., balance in check writing )

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Part III System Analysis and Design; Programming

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### Part IIISystem Analysis and Design; Programming

• Decision Support Systems

• Pictorial Model

• Tools: Excel, VBA, IFPS

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### Decision Support Systems(1.2)

• Supports Decisions

• Must identify decision criteria (e.g., balance in check writing)

• “Functions” for most frequently used (significant few) tools

• Programming tools for “trivial many” customization

### Pictorial Model

• Modeling (1.2) (Transformation Function, what is it? what are the significances of using this term?)

### Pictorial Model

• Consists of Pictorial Diagram and equations (pp. 2-3, 5-2)

• Uses numbers to identify equations and their sequence

• The number of lines out of an attribute indicates its influence to the entire model.

### Pictorial Model

• Boundary variables have no predecessor

• Boundary variables will become “assumptions” in IFPS programs

### Tools: Excel

• Quick solution; ready-to-use functions (e.g., pmt, stdevp)

• Once set up, users can change input parameters (e.g., interest rate, loan amount) to “reuse” this “program”

• Not as flexible but less knowledge in programming is needed.

### Tools: VBA

• For any programming language, must know “input” and “output” first

• All programs can be broken down to sequential, iterative (loops), and selection (if-then)

• VBA uses spreadsheet as the source of data (input) and display of results (output) -- see handouts

### Tools: VBA

• More flexible (e.g., length of annuity table does not have to be pre-determined)

• Programming idiosyncrasies (e.g., ‘=‘ means assign and not equal)

• Most fundamental functions: a=a+1 (counter) and sum=sum+a

• for-next loop and if-then-else (see handouts)

### Standard Deviation Example

• For Logical Design step, research the process by reading books (document) and look for formula (form)

• Definitional Formula is easier to understand (why?)

• Computational Formula is more efficient (why?)

### Tools: IFPS

• 4GL (see 1.3 and 1.6)

• Extract equations (i.e., business model) from descriptions

• Organize the pictorial diagram starting with the goal (e.g., profit) and work backwards

• Once the pictorial model is done, the IFPS program is basically done as well.

### Tools: IFPS

• Compared to Excel, IFPS can do what-if analysis (manipulate input variables) as well

• Goal seeking allows user to pre-determine the outcome and view the possible choice of input variables

• Simple graphics and report generation for final decision making

### Economic Analysiswhy graphics?

• Direction and Magnitude (slope of a curve, coefficient for regression line)

• Graphics allow a quick view of the long-term trend

• Knowledge of the attributes is more important than the knowledge of the tools

• Knowledge of the tool enhances the ability to analyze

### Tools: IFPS

• “Right” is subjective

• Easy-to-use modeling tool (compared to Excel and VBA) allows the management to move into Physical Design and Implementation/ Testing stage (End-user development in Laudon chapter 11, p. 349)