Objetivos e hipótesis

Suppose that you are working with Rick and Carla when a new systems request comes in. SWL’s vice  president of marketing, Amy Neal, wants to change the catalog mailing program and provide a reward for customers who use the Internet.

Amy’s plan specifies that customers will remain on SWL’s mailing list if they either requested a  catalog, ordered from SWL in the last two years, or signed the guest register on SWL’s new Web site. To  encourage Internet visitors, customers who register on the Web site also will receive a special discount  certificate.

To document the requirements, Rick wants you to design a decision table. Initially, it appears to  have eight rules, but you notice that some of those rules are duplicates, or might not be realistic 

combinations.

1. Design the decision table with all possibilities.

The three separate conditions should produce a total of eight possible rules, and the table should look something like the following example:

RULES 1 2 3 4 5 6 7 8

Requested a catalog

Y Y Y Y N N N N

Ordered in past two years

Y Y N N Y Y N N

Signed Web site register

Y N Y N Y N Y N

Remain on mailing list

X X X X X X X

Receive

certificate X X X X

2. Simplify the table by combining rules where appropriate.

Now the rules can be simplified by considering the following:

a. If a customer registers on the Web site, as in Rules 1, 3, 5, and 7, he or she stays on the mailing list and gets the discount certificate. In this situation, the other two conditions do not really matter.

b. If a customer did not register on the Web, then it does matter whether they fulfilled the other conditions. In Rules 2 and 4, the catalog request was present and the 2-year rule does not matter. In Rule 6, the 2-year rule was fulfilled and the catalog request does not matter.

c. If none of the conditions is fulfilled, as in Rule 8, the customer is removed from the mailing list and does not receive the discount certificate.

The following table shows the simplification just described:

RULES 1 2 3 4 5 6 7 8 Requested a

catalog

- Y - Y - - - N

Ordered in past two years

- - - Y - N

Signed Web site register

Y N Y N Y N Y N

Remain on mailing list

X X X X X X

Receive

certificate X X X X

Finally, based on the analysis described in Step 2, the original eight rules can be combined into just four rules, as follows:

RULES 1 2 3 4

Requested a catalog

- Y - N

Ordered in past two years

- - Y N

Signed Web site register

Y N N N

Remain on mailing list

X X X

Receive

certificate X

3. Draw a decision tree that reflects Amy Neal’s policy.

Using the same logic, the decision tree will produce the four rules shown in the final version of the decision table. The layout of the tree will vary depending on which condition is depicted first. The simplest solution is to start with the Web site condition, as follows:

Remain on mailing list and receive certificate Signed Web site register

Requested a catalog Did not sign register

Ordered in past two years

Did not order in past two years

Remain on mailing list Remain on mailing list

Remove from mailing list Did not request a catalog

4. Create a set of structured English statements that accurately describes the policy.

Students should review the example in Figure 5-33 on page 225 and use their imagination for this assignment. Explain that the objective is to come up with a reasonable example of structured English — not a detailed process description. A sample solution might look like the following:

For each CUSTOMER

If REGISTERED ON WEB SITE Else

If CATALOG REQUESTED or ORDERED IN 2 YEARS Else

Remove from mailing list Remain on mailing list

Remain on mailing list and receive certificate

Manage the SWL Project

You have been asked to manage SWL’s new information system project. One of your most important activities will be to identify project tasks and determine when they will be performed.

Before you begin, you should review the SWL case in this chapter. Then list and analyze the tasks, as follows:

LIST THE TASKS Start by listing and numbering at least ten tasks that the SWL team needs to perform to fulfill the objectives of this chapter. Your list can include SWL Team Tasks and any other tasks that are described in this chapter. For example, Task 3 might be to Identify the system entities, and Task 6 might be to Draw a context diagram.

An answer might include tasks listed in the Chapter Introduction Case, and other examples of tasks found in the SWL case or elsewhere in the chapter. A sample answer follows:

Task List

 Learn how to use data flow diagrams, data dictionaries, and process description tools

 Learn how to use the four main DFD symbols

 Understand leveling and balancing concepts

 Create a data dictionary that will document the DFDs

 Create a context diagram

 Create a diagram 0 DFD

 Create lower-level diagrams

 Check to assure that all DFDs are leveled and balanced

 Describe all processes using structured English, decision tables and decision trees

 Complete a logical data and process model of the system

ANALYZE THE TASKS Now study the tasks to determine the order in which they should be performed. First identify all concurrent tasks, which are not dependent on other tasks. In the example shown in Figure 5-47, Tasks 1, 2, 3, 4, and 5 are concurrent tasks, and could begin at the same time if resources were available.

Other tasks are called dependent tasks, because they cannot be performed until one or more earlier tasks have been completed. For each dependent task, you must identify specific tasks that need to be completed before this task can begin. For example, you would want to identify the system entities before you could draw a context diagram, so Task 6 cannot begin until Task 3 is completed, as Figure 5-47 shows.

Answers will vary. A sample answer follows:

Concurrent Tasks Dependent Tasks

1. Learn how to use data flow diagrams, data dictionaries, and process description tools

4. Create a data dictionary that will document the DFDs

2. Learn how to use the four main DFD symbols

5. Create a context diagram 3. Understand leveling and balancing

concepts 6. Create a diagram 0 DFD

7. Create lower-level diagrams 8. Check to assure that all DFDs are leveled and balanced

9. Describe all processes using structured English, decision tables, and decision trees 10. Complete a logical data and process model of the system

For each dependent task, a sample list of predecessor tasks follows:

Dependent Tasks Predecessor Tasks

4. Create a data dictionary that will

document the DFDs 1,2,3

5. Create a context diagram 4

6. Create a diagram 0 DFD 5

7. Create lower-level diagrams 6 8. Check to assure that all DFDs are

leveled and balanced

7 9. Describe all processes using structured English, decision tables, and decision trees

8 10. Complete a logical data and process

model of the system 9

Chapter 3 describes project management tools, techniques, and software. To learn more, you can visit the Features section on your Student Study Tool CD-ROM, or visit the

Management Information Systems CourseMate Web site at www.cengagebrain.com and locate the project management resources library for this book. On the Web, Microsoft offers demo versions, training, and tips for using Project 2010. You also can visit the

OpenWorkbench.org site to learn more about this free, open-source software.

The Features section on the Student Study Tool CD-ROM includes Web links for Microsoft Project and Open Workbench, and a user guide for Open Workbench. Instructors can

demonstrate Microsoft Project if it is available, and show students how to download and install Open Workbench. Instructors also can create additional assignments that use project

management software skills in a systems development environment.