chapter 10 the rea approach to business process modeling
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CHAPTER 10 THE REA APPROACH TO
BUSINESS PROCESS MODELING REVIEW QUESTIONS 1. A user view is the set of data that a particular user needs to achieve his or
her assigned tasks. 2. It is frameworks for designing accounting information systems that captures
the operational meaning of the user's data and provides a concise description of it.
3. It is a unique version of an ER diagram consisting of three entity types (resources, events, and agents) and a set of associations linking them.
4. Economic resources are those things of economic value that are both scarce and under the control of the enterprise.
5. Economic events are phenomena that affect changes (increase or decrease) in resources.
6. Support events include control, planning, and management activities that are related to economic events, but do not directly affect a change in resources.
7. Economic agents are individuals and departments that participate in an economic event. They are parties both inside and outside the organization with discretionary power to use or dispose of economic resources.
8. Each economic event in an exchange is mirrored by an associated economic event in the opposite direction.
9. View modeling is a process in which the database designer identifies and models the set of data that individual users need. The result of this process is an ER diagram depicting the users data model.
10. The labeled line represents the association or nature of the relationship between entities.
11. Traditional accounting activities such as recording a sale in the journal and setting up an account receivable are not value chain activities and need not be modeled. Capturing transaction data in sufficient detail adequately serves traditional accounting requirements.
12. Association is the nature of the relationship between two entities and is represented by the labeled line connecting them.
13. Cardinality describes the number of possible occurrences in one entity that are associated with a single occurrence in a related entity.
14. The four basic forms of cardinality are: zero or one (0,1), one and only one (1,1), zero or many (0,M), and one or many (1,M).
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15. It is the process of combining multiple individual REA diagram into an integrated global or enterprise model.
16. The steps involved in view integration. 1. Consolidate the individual models 2. Define primary keys, foreign keys, and attributes
3. Construct Physical database and Produce User Views 17. Typically one of the tables in a 1:1 association has a minimum cardinality of
zero. When this is the case, the primary key of the table with the (1,1) cardinality should be embedded as a foreign key in the table with the (0,1) cardinality.
18. The primary key of the 1 side table is embedded as a foreign key in the table of the M side.
19. Tables in an M:M association cannot accept an embedded foreign key from the related table. Instead, a separate link table must be created to contain the foreign keys.
20. These are the activities that add value or usefulness to an organizations products and services.
DISCUSSION QUESTIONS 1. An economic exchange is a pair of mirrored economic events: the give event
and receive event. From the perspective of the organization function being modeled, the give half of the exchange decreases the economic resource, as represented by the outflow association. The receive half of the exchange increases the economic resources represented by an inflow association.
2. The upper cardinalities for each of the two related entities define the overall association between them. For example, if the cardinality at one end of the association line is (0,1) and at the other end it is (1,M) then the association between them is one-to-many (1:M).
3. The database designer should select a primary key that logically and uniquely defines the nonkey attributes in the table. In some cases this is accomplished with a simple sequential code such as an Invoice Number, Check Number, or Purchase Order number. In other situations block codes, group codes, alphabetic codes, and mnemonic codes, are better choices.
4. Each event must be linked to at least one resource and a least two agents. One of the agents is internal to the organization and the other is usually external. In some types of transaction, however, the second agent may also be internal.
5. The convention in an REA diagram is to treat such transactions as if they are sales. The clerk giving up control and reducing the resource (raw materials) is the internal agent and the clerk assuming control and increasing the resource (work-in-process) is the external agent.
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6. Journals, ledgers, and double-entry bookkeeping are the traditional mechanisms for formatting and transmitting accounting data, but they are not essential elements of an accounting database. REA systems capture the essence of what accountants account for by modeling the underlying economic phenomena directly. Organizations employing REA can thus produce financial statements, journals.
7. Economic events are phenomena that affect changes (increase or decrease) in resources. Examples include sales of products to customers, receipt of cash from customers, and purchases of raw material from vendors. Support events include control, planning, and management activities that are related to economic events, but do not directly affect a change in resources. Examples of support events include: 1) determining inventory availability for a customer prior to a sale, 2) verifying supporting information (performing a three-way-match) prior to disbursing cash to a vendor, and 3) checking customer credit before processing a sale.
8. An REA model must, as a minimum, include the two economic events that constitute the give and receive activities that reduce and increase economic resources in the exchange. In addition it may include support events, which do not change resources directly.
9. REA is modeling focuses on value chain activities: those that use cash to obtain resources such as equipment, materials, and labor and those that employ these resources to earn new revenues. Traditional accounting events such as recording a sale in the journal and setting up an account receivable are not value chain activities and need not be modeled. Capturing transaction data in sufficient detail adequately serves traditional accounting requirements.
10. The inclusion of link tables in a REA diagram creates a conflict with the rule that an event entity should be connected to at least one resource and at least two agent entities. Although link tables are a technical requirement for implementing a M:M association in a relational database, they are not a technical requirement for modeling the database. Including the link table in an REA diagram disrupts its visual integrity and adds little to the conceptual model. During implementation, the database designer will create the link tables needed to make the database function.
11. Unlike tangible economic resources such as cash and inventory, time does not have a stock flow element and cannot be stored. It is increased simultaneously decreased by various employee activities. In situations where employee services are directly tracked to products produced or services rendered to clients (i.e., consulting or public accounting) it makes sense to model this resource. In situations where employee time on the job is not tracked to specific results then modeling this entity and transforming it into a physical database table serves no purpose.
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12. Normalization is the process of systematically identifying and removing repeating groups, partial dependencies, and transitive dependencies from the table(s) under review. Tables in 3NF will be free of anomalies and will meet two conditions:
1) All nonkey attributes will be wholly and uniquely dependent on (defined by) the primary key.
2) None of the nonkey attributes will be dependent on (defined by) other nonkey attributes.
MULTIPLE-CHOICE QUESTIONS 1. e 2. d 3. c 4. e 5. c 6. a 7. c 8. c 9. c 10. c
PROBLEMS 1. The three differences between REA diagrams and ER diagrams:
1) Entities on REA diagram, are divided into three classes (Resources, Events, and Agents) and organized into constellations by class on the diagram. Entities in ER diagrams are of one class and their proximity to other entities is determined by their cardinality and by what is visually pleasing to keep the diagrams readable.
2) ER diagrams present a static picture of the underlying business phenomena. Relationships between data are shown through cardinality and associations, but the sequence of activities that determine the cardinality and associations are not clearly represented. REA diagrams, however, are typically organized from top to bottom within the constellations to focus on the sequence of events.
3) The third difference between ER and REA diagrams pertains to naming conventions for entities. In ER diagrams, entity names are always represented in the singular noun form. REA modeling applies this rule when assigning names to resource and agent entities. Event entities, however, are given verb (action) names such as Sell Inventory, Take Order, or Receive Cash.
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2. B is the correct association. Each Sell Auto event could involve one or many autos but each auto in inventory is unique and can be sold only once or has not yet been sold.
3. The proper association is C. Each cash receipt is for only one Sell Auto event and each Sell Auto event requires one immediate payment in full. Bentley should never have a situation where a record exists in the Sell Auto table without a corresponding record in the Receive Cash table.
4. B is the proper association. Each customer may buy zero or many times from Bentley but each sale is to only one customer.
5.
Resources Events Agents
Raw MaterialInventory Pick Inventory
Warehouse Clerk
Finished Goodsinventory Produce Production Worker
Causes
Increases
Reduces
Performs
Requests
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6.
Book Inventory
Take Order
Customer
SalesClerk
ReducesProcess Order
Cash
Purchases
Relatedto
Query AvailabilityReview Items
Requests
Receives Cash
Customer
Duality
Remits
Increases
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7. REA Model - Feinman Computers
ANSWER A and B:
Inventory Take Order
Customer
Sales ClerkReserves
ProcessOrder
Increases Receive Cash Cash ReceiptsClerk
Shipping Clerk
Cash
Places Order
ProcessesRemittance
Ship Product
Causes
Customer
Reduces
Duality
Ships
Remits
Receives
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ANSWER C
Table Name Primary Key Foreign Key(s) Attributes
Inventory Item Number Description, Warehouse Location, Quantity on Hand, Reorder Point, On-Order Quantity, Available for Sale, Supplier Number, Unit Cost, Retail Price
Cash Account
Take Order
Ship Product
Receive Cash
Invoice Amount, Shipped Date, Due Date, Close Invoice Order Number Customer Number Employee Number
Order Inquiry Number Customer Number Employee Number
Order Date, Promised Date, Terms Of Trade,
Remittance Customer Number Employee number Account Number
Customer Check Number, Date, Amount
Balance
Supplier
Customer
Employee
Customer Number Name, Address, Line of credit, Available Credit, Current Balance Last Payment Date
Employee Number SSN, Name, Address, Date of Birth, Job Title, Data Hired, Pay Rate, Vacation Time Accrued
Supplier Number Name, Address, Terms of Trade, Vendor lead time, Carrier used, On-time delivery record, Incomplete shipments record, Damaged shipments record, Price disputes record
Table Name
Inventory-Order Link
Inventory-Ship Link
Primary Key Attributes
Item Number Order Number
Quantity Ordered
Item Number Invoice Number Quantity Shipped, Actual Price
Linking Tables
Problem 10 - 7 Tables, Keys, and Attributes for Feinman Computers
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8. REA Model - K Cannon, Inc.
ANSWER A and B:
Inventory Order Product Purchasing Clerk
Supplier
Receive Product
Disburse CashCashCashDisbursementClerk
Supplier
Receiving
ProcessesFlags Item
Increases
Causes
Duality
Receives
Ships
Prepares
Receives
ProcessesDecreases
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ANSWER C.
Problem 10- 8 Tables, Keys, and Attributes for K Cannon Inc.
Linking Tables
Table Name Primary Key Foreign Key(s) Attributes
Inventory Item Number
Description, Warehouse Location, Quantity on Hand, Reorder Point, On-Order Quantity, Available for Sale, Supplier Number, Unit Cost, Retail Price. Turnover rate, Lead time, Usage rate, Economic order quantity, Stockout history, Scrap history
Cash Account Balance
Supplier
Employee Employee Number SSN, Name, Address, Date of Birth, Job Title, Data Hired, Pay Rate, Vacation Time Accrued
Supplier Number
Name, Address, Terms of Trade, Vendor lead time, Carrier used, On-time delivery record, Incomplete shipments record, Damaged shipments record, Price disputes record
Disburse Cash
Receive Product
Order Product Purchase Order Supplier NumberOrder Date, Expected Delivery Date, Expected Total Price
Receiving Report Supplier Number Employee Number Purch Order Number Check Number
Date Received, Carrier, Total Amount Due, Due
Check Number Amount, DateSupplier Number Cash Disb Clerk (EMPL) Account Number
Ord-Prod-Inven Link
Rec-Prod-Inven Link
Item Number Purchase Order Number Order Quantity
Item Number Receiving Report Quantity Received, Actual Unit Cost, Condition
Table Name Primary Keys Attributes
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9. REA Model -Payroll System
ANSWER A and B:
NOTE: The task of preparing the payroll register described in the case is not an REA event and should not be modeled. This is an accounting activity. All attributes needed to perform this activity are captured in the Get Time and Disburse Cash event tables. The payroll register is simply a view that may be prepared from these tables.
Problem 10- 9 Tables, Keys, and Attributes
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10. REA Model - Fixed Asset System
ANSWER A and B:
NOTE: The task of recording depreciation is not an REA event and should not be modeled in an REA diagram. Depreciation is an accounting technique that arbitrarily allocates some of the cost of the asset to various periods. Information about the depreciation method and accumulated depreciation is stored in the Fixed Asset Inventory table to support the task of reporting periodic depreciation charges. The calculation process is, however, not an event.
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ANSWER C.
Problem 10-10 Tables, Keys, and Attributes
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