TUTORIAL BUILDING A DECISION SUPPORT SYSTEM IN EXCEL A decision support systenl (DSS) is a computer program that can represent a problem a user neetls to solve. Such a representation is in effect a model of a problem. Here's how a USS program works: The program accepts input from the user or accesses data in the sys- tem's files and then runs the input and any other necessary data through the model. The program's output is the information the user needs to solve a problem. Seine DSS programs recommend a solution to a problem. A USS can be written in any programming language that lets a programmer represent a problem. For example, a USS can be built in a third-generation language such as Visual Basic or in a database package such as Access. A USS can also be written in a spreadsheet package such as Excel. Excel has standard, built-in arithmetic functions as well as many statistical and financial functions. Thus, many kinds of problemssuch as those in accounting, operations. and nancecan be modeled in Excel. This tutorial is organized into four sections as follows: 0 Spreadsheet. and D88 BasicsIn this section. you'll learn how to create a D88 program in Excel. Your program will be in the form of a cash ow model. This section will give you practice in spreadsheet design and in building a D88 program. 0 Using Scenario Manager In this section, you'll learn how to us ' an Excel tool called Scenario Manager. With any USS package. one problem with playing \"what if\" is deciding where to physi- cally record the results from running each set of data. A user cotlld write the inputs and related results on a sheet of paper. Then, the user might have to enter the data back into a spreadsheet for further analysis. Scenario Manager solves this problem. It can be set up to capture inputs and related results as \"scenarios,\" which are then summarized on a separate sheet in the Excel workbook. 0 Practicing with Scenario R-lanager'i'ou will work on a. new case problem using Scenario Manager. 0 Reviewing Excel Basics'I'his section reviews additional in formation you may need to do the spreadsheet. cases that follow this tutorial. SPREADSHEET AND DSS BASICS Assume it is late in Year 1 of a three-year period, and you are trying to build a model of a company's net income (profit) anti cash flow for Years 2 and 3. The problem is to forecast net income anti cash flow in those years. The company is likely to use the forecasts to make decisions, so the estimates should be as accurate as you can make them. After researching the problem, you decide that the estimates should be based on three factors: (1) Year 1 results, [2) estimates of the underlying economic variables, and (3} the cost of products the company sells. Your model will use an income statement and cash flow framework. The user can enter values for two pos- sible states of the economy in Years 2 and 3: an 0 for an optimistic outlook or a l' for a pessimistic outlook. The state of the economy is expected to affect the n timber of units the company can sell as well as each unit's selling price. In a good (optimistic) economy, more units can he sold at a higher price. The user can also enter values into your model to see two possible trends in the cost of goods sold: U for up or D for down. A U means that the cost of an item sold will be higher than it was in Year 1; a D means that the cost will be less. Presumably, the company will do better in a good economy and with lower input costsbut how much better? The user can play \"what if" with the input variables antl note the effect on net income and year-end