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MIS II Exam #2
Process and Conceptual Data Modeling
| Question | Answer |
|---|---|
| What is process modeling? | Graphically represents the processes that capture, manipulate, store, and distribute data between a system and its environment among system components |
| What is a data flow diagram (DFD)? | Graphically illustrates the movement of data between external entities and the processes and data stores within a system |
| What are the deliverables of process modeling (4)? | (1) Data-flow diagram of current system (2) New logical DFD system (3) Project Dictionary (4) Case Repository |
| How do you model a system's process? | By utilizing information gathered during requirements determination |
| What are the symbols in diagramming mechanics (4)? | (1) data flow (2) data store (3) process (4) source/sink |
| What is data flow? | Depicts data that are in motion and moving as a unit from place to another in the system. Drawn as an arrow |
| What is a data store? | Depicts data that is at a resting point: file folder, computer-based file, notebook. Drawn as a rectangle |
| What is a process? | Depicts work or actions performed on data so that they are transformed, stored, or distributed. Drawn as a rectangle with rounded corners |
| What is a source/sink? | Depicts the origin and/or destination of the data. External agents in the process: customer, accounting department, bank. Drawn as a square symbol |
| What is a context diagram? | A data-flow diagram of the scope of an organizational system that shows the system boundaries, external entities that interact with the system and the major information flows between the entities and the system |
| What is a Level-O Diagram? | A data-flow diagram that represents a system's major processes, data flows, and data stores at a "higher level" |
| What are the basic rules of DFDs (2)? | (1) inputs to a process are always different than their outputs (2) All objects have a unique name |
| What are the rules of data stores (4)? | (1) Data cannot be moved from one store to another (2) Data cannot move from an outside source to a data store (3) Data cannot directly move from a store to a sink (4) Has a noun phrase label |
| What are the rules of source/sink (2)? | (1) Data cannot directly move from a source to a sink (2) A source/sink has a noun phrase label |
| What are the rules of data flow (5)? | (1) Data flows only one direction (2) A fork means that the exact same data goes from one location to two or more locations (3) A join is the opposite of a fork (4) data flow cannot go to same process it leaves (5) data flow to a store means update |
| What is functional decomposition? | Act of going from one single system to many component processes in a repetitive procedure |
| What are level-n diagrams? | A DFD that is the result of n nested decompositions of a series of subprocesses on a level-O diagram |
| What does it mean to balance DFDs? | To conserve inputs and outputs from a process at the next level of decomposition |
| What does completeness mean in process modeling? | DFD must include all components necessary for the system. Each components must be described in project dictionary or CASE repository |
| What does it mean to have consistency in process modeling? | The extent to which information contained on one level of a set nested DFDs is also included on other levels |
| How is timing a factor in process modeling? | Time is not represented well on DFDs. It is best to draw the diagram as if the system has never started and will never stop |
| What is iterative development? | Analyst should expect to redraw diagram several times before reaching closest approximation to the system being modeled |
| What are primitive DFDs? | The lowest logical level of decomposition. Decision has to be made when to stop decomposition |
| What are the rules for stopping decomposition (1-4)? | (1) When each process has been reduced to a single outcome (2) When each data store represents a single entity (3) When the system user does not need anymore detail (4) When every data flow does not need to handled in different ways |
| What are the rules for stopping decomposition (5-6)? | (5) When you believe that you have shown each business form or transaction, online display and report as a single data flow (6) When you believe that there is a separate process for each choice on all lowest-level menu options |
| What is gap analysis? | The process of discovering discrepancies between two or more data sets of data-flow diagrams or discrepancies within a single DFD |
| What is logic modeling? | Representing internal structure and functionality of processes depicted on a DFD |
| What are decision tables? | A matrix representation of the logic of a decision that specifies the possible conditions and the resulting actions |
| What are the decision tables parts (3)? | (1) Condition Stubs (2) Action Stubs (3) Rules |
| What are condition stubs? | Lists conditions relevant to decision |
| What are action stubs? | Actions that result for a given set of conditions |
| What are decision table rules? | They specify which actions are to be followed for a given set of conditions |
| What is an indifferent conditions? | Condition whose value does not affect which action is taken for two or more rules |
| What is the standard procedure for creating decision tables? (6) | (1) Name the conditions and values each condition can assume (2) Name all possible actions that can occur (3) Name all possible actions that can occur (4) list all possible rules (5) Define the actions for each rule (6) simplify the decision table |
| What is conceptual data modeling? | Representation of organization data that shows the rules and meaning among data |
| What are the collection methods for ER diagrams (3)? | (1) Interviewing (2) Questionnaires (3) JAD |
| What is the goal of conceptual data modeling? | To create accurate entity-relationship (ER) diagrams |
| What are the steps in conceptual data modeling? | (1) Develop a data model for the system being replaced (2) New data model is built with all requirements |
| What is the design stage of conceptual data modeling? | When the conceptual data model is translated into a physical design |
| What is a project repository? | Links all design and data modeling steps performed during SDLC |
| How many E-R diagrams can be produced during conceptual data modeling? | FOUR |
| What is top-down collection? | Data model is derived from an intimate understanding of the business. Bigger problems than smaller ones |
| What is bottom-up collection? | Data model is derived from reviewing specifications and business documents |
| What are the notation constructs? | (1) Data entities (2) relationships (3) Attributes |
| What is a entity-relationship diagram? | A detailed, logical, and graphical representation of entities, associations, and data elements that are involved in an organization or business |
| What is an entity? | A person, place, object, event, or concept in the user environment about which the organization wishes to maintain data. Represented by a triangle |
| What is an entity type? | A collection of entities that that share common properties or characteristics |
| What is an entity instance? | A single occurrence of an entity type |
| What is an attribute? | A named property or characteristic of an entity that is of interest to an organization |
| What is the candidate key and identifier rule? | Each entity type must have an attribute or set of attributes that distinguishes one instance from other instances of the same type |
| What is a candidate key? | Attribute that uniquely identifies each instance of an entity type |
| What are the minimum requirements on alternative design? | The mandatory features that re different than desired features |
| What are the features in alternative designs (4)? | (1) Data (2) Outputs (3) Analyses (4) User expectations on accessibility |
| What are the constraints in alternative design (5)? | (1) Time (2) Finances (3) Unchangeable elements (4) legal (5) dynamics of the problem |
| What is an identifier? | A candidate key that has been selected as the unique identifying characteristic for an entity type |
| What are the selection rules for an identifier (4)? | (1) Choose a candidate key that will not change its value (2) Choose a candidate key that will never be null (3) Avoid using intelligent keys (4) Consider substituting single value surrogate keys for a large composite key |
| What is a multivalued attribute? | An attribute that may take on more than one value for each entity instance |
| What are the graphical representations for a multivalued attribute? (2) | (1) Double-Lined Ellipse (2) Weak Entity |
| What is a relationship in conceptual data modeling? | An association between instances of one or more entity types that is of interest to the organization. Always labeled with verb phrases |
| What is the goal an entity-relationship diagram? | Capture as much of the meaning of the data as possible |
| What is the result of an entity-relationship diagram? | A better design that is easier to maintain |
| What is a degree in conceptual data modeling ? | Number of entity types that participate between the instances of two entity types |
| What are the types of relationships in conceptual data modeling (3)? | (1) Unary (2) Binary (3) Ternary |
| What is a unary relationship? | A relationship between the instances of one entity type |
| What is a binary relationship? | A relationship between the instances of two entity types |
| What is a ternary relationship? | A relationship between the instances of three entity types |
| What does cardinality mean? | The number of instances that entity B can be associated with each instance of entity A |
| What does minimum cardinality mean? | The minimum number of instances of entity B that may be associated with each instance of entity A |
| What does maximum cardinality mean? | The maximum number of instances of entity B that may be associated with each instance of entity A |
| What is an associative entity? | An entity type that associates the instances of one or more entity types and contains attributes that are peculiar to the relationship between those entity instances |
| What are the steps in selecting best alternative design strategy (2)? | (1) Generate a comprehensive set of alternative design strategies (2) select one design strategy that is most likely to result in the desired information system |
| What is a low-end alternative design strategy? | A design that provides all required functionality that users demand with a system that is minimally different from the current system |
| What is a high-end alternative design strategy? | A design that solves problems in question and provides many extra features users desire |
| What is a mid-range alternative design strategy? | Compromise of features in high-end alternative with frugality of low-end alternative |
| What are the guidelines for drawing DFDs (5)? | 1. Completeness 2. Consistency 3. Timing Considerations 4. Iterative Nature of DFDs 5. Drawing Primitive DFDs |
| What is the deliverable of the conceptual modeling phase? | Entity-Relationship Diagram |
| What are the different types of relationship cardinality (4)? | (1) Mandatory one (2) Mandatory many (3) Optional One (4) Optional many |
| What are the different types of entity types? (3) | (1) Strong (2) Weak (3) Associative |
| What is a repeating group? | A set of two or more multivalued attributes that are logically related |
| What represents "mandatory one"? | Two Lines |
| What represents "mandatory many"? | One line & Crows foot |
| What represents "optional one"? | One line & Circle |
| What represents "optional many"? | Circle & Crows foot |
| What is a design strategy? | A particular approach to developing an information system. It includes statements on the system’s functionality, hardware and system software platform, and method for acquisition |
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legitcow3
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