MIS 3360 EXAM 2

Secondary key

1 or + combination of fields for which more than 1 row may have the same combination of values

Indentifier

A candidate key that has been selected as unique, identifying characteristics for an entity type

Data type

coding scheme recognized by system software for representing organizational data

Data store

data at rest, which may take the form of many different physical representations

Relational database model

data represented as set of related tables of relations

Calculated field

field that can be derived from other database fields. Also known as computed field or derived field - common for attribute to be mathematically related to other data - calculate value is either stored of computed when requested

Indexed file organization

file organization in which rows are stored either sequentially or nonsequentially, and an index is created that allows software to locate individual rows

Indifferent condition

in a decision table, a condition whose value does not affect which actions are taken for 2 or + rules

Physical file

named set of table rows stored in contiguous section of secondary memory (result of denormalization)

Normalization

process of converting complex data structures into simple, table data structures

Denormalization

process of splitting or combining normalized relations into physical tables based on affinity of use of rows and fields

Close-ended questions

questions in interviews that ask those responding to choose from among a set of specified responses - includes: T or F, multiple choice, rating a response or idea on a scale, ranking items in order of importance

Open-ended questions

questions in interviews that have no prespecified answers

Field

smallest unit of application data recognized by system software, such as programming language or database management system - attributes from relations will represented as fields

Business rules

specifications that preserve the integrity of the logical data model - captured during requirements determination - stored in CASE repository as they are documented

Overlap rule

specifies that an entity instance can simultaneously be a member of 2 or + subtypes

Partial specialization rule

specifies that an entity instance of the supertype must be a member of some subtype of the relationship

Total specialization rule

specifies that each entity instance of the supertype

Disjoint rule

specifies that if any entity instance of the supertype is a member of one subtype, it cannot simultaneously be a member of any other subtype

Index

table used to determine location of rows in file that satisfy some condition

File organization

technique for physically arranging the records on file

Disruptive technologies

technologies that enable the breaking of long held business rules that inhibit organizations from making radical business changes

Balancing

the conservation of inputs and outputs to a DFD process when that process is decomposed to a lower level - number of inputs to lower level DFD equals number of inputs to associated process of higher-level DFD - number of outputs to lower level DFD equals number of outputs to associated process of higher-level DFD

Present value

the current value of a future cash flow

DFD completeness

the extent of which all necessary components of DFD has been included and fully described

DFD consistency

the extent to which information contained on one level of a set of nested DFDs is also included in other levels

Business case

the justification for an information system, presented in terms of the tangible and intangible economic benefits and costs and the technical and organizational feasibility of the proposed system

Primitive DFD

the lowest level of decomposition for a DFD

Degree

the number o any entity types that participate in a relationship

Cardinality

the number of instances of entity B that can (or must) be associated with each instance of entity B

Formal system

the official way a system works as described in organizational documentation - e.g. work procedure

Source/sink

the origin and/or destination of data; sometimes referred to as external entities

Action subs

the part of a decision table that lists actions that result for a given set of conditions

Rules

the part of a decision table that specifies which actions are to be followed for a given set of conditions

Scribe

the person who makes detailed notes of the happenings at a JAD session

Legal and contractual feasaibility

the process of assessing potential legal and contractual ramification due to the construction of a system

Operational feasability

the process of assessing the degree to which a proposed system solves business problems or takes advantages of business opportunities

Schedule feasability

the process of assessing the degree to which the potential time frame and completion dates for all major activities w/in a project meet organizational deadlines and constraints for affecting change

Gap analysis

the process of discovering discrepancies b/t 2 or + sets of DFDs or discrepancies w/in a single DFD - inefficiencies in system can often be ID'd through DFD

Political feasability

the process of evaluating how key stakeholders w/in organization view the proposed system

Discount rate

the rate of return used to compute the present value of future cash flows

Business processing reengineering (BPR)

the search for, and implementation of, radical change in business processes to achieve breakthrough improvements in products and services

Domain

the set of all data types and values that an attribute can assume Advj: - verify that values for attribute are valid - ensure various data manipulation operations are logical - help conserve effort in describing attribute characteristics

Key business processes

the structured, measured set of activities designed to produce a specific output for a particular customer or market

JAD session leader

the trained individual who plans and leads Joint Application Design sessions

Default value

the value a field will assume unless and explicit value is entered for the field

Informal system

the way a system actually works -e.g. interviews and observations

Process

the work or actions performed on data so that they are transformed, stored or distributed

Synonym

two different names that are used for the same attribute

Level-n diagram

a DFD that is the result of n nested decomposition from process on a level-0 diagram

Level-0 diagram

a DFD that represents a system's major processes, data flows and data stores at a high level of detail - Processes are labeled 1.0, 2.0, etc. These will be decomposed into more primitive (lower-level) DFDs

Tangible benefit

a benefit derived from the creation of an information system that can be measured in dollars and with certainty - e.g. reduced personnel expenses, lower transaction costs or higher profit margins - will fit in categories like cost reduction and avoidance, error reduction, increased flexibility, increased speed and activity, improvement of management planning and control, opening new markets and increasing sales opportunities

Intangible benefits

a benefit derived from the creation of an information system that cannot be easily measured in dollars or with certainty - may have direct organizational benefits such as improvement of employee morale - may have broader societal implications such as reduction of waste creation or resource consumption

Functional dependency

a constraint b/t 2 attributes in which value of one attribute is determined by value of another attribute - for given relation, attribute B is functionally dependent on attribute A if, for every valid value of A, the value of A unique determines value of B - functional dependency of B on A is represented by A->B - no mathematical calculation dependence, rather it means that there can be only one value of B for each value of A

One-time cost

a cost associated w/project start up and development or system startup - encompass activities such as systems development, new hardware and software purchases, user training, site preparation, and data or system conversion - consists of items that are fixed or variable in nature

Tangible cost

a cost associated with an information system that can be measured in dollars and with certainty - include hardware costs, labor costs or operational costs including employee training and building renovations

Recurring cost

a cost resulting from the ongoing evolution and use of a system - e.g. include application software maintenance, incremental storage expenses, incremental communications, new software and hardware leases and supplies and other expenses - consists of items that are fixed and variable in nature

Entity-relationship data model (E-R model)

a detailed, logical representation of entities, associations and data elements for an organization or business area

Project scope statement (PSS)

a doc prepared for customer that describes what the project will deliver and the outlines generally at a high level all work required to complete the project

Nominal group technique

a facilitated process that supports idea generation by groups. At the beginning of the process, group members works alone to generate ideas, which are then pooled under the guidance of a trained facilitator

Pointer

a field of data that can be used to locate a related field or row of data

Sequential file organization

a file organization in which rows in a file are stored in sequence according to a primary key value

Hashed file organization

a file organization in which the address of each row is determined using an algorithm

Recursive foreign key

a foreign key in a relation that references the primary key values of same relation

Entity-relationship diagram

a graphical representation of the E-R model

Baseline project plan (BPP)

a major outcome and deliverable from the project initiation and planning phase that contains the best estimate of a project's scope, benefits, costs, risks and resource requirements

Decision table

a matrix representation of the logic of a decision, which specifies the possible conditions for the decision and the resulting actions

Physical table

a named set of rows and columns that specifies fields in each row of the table

Relation

a named, 2-D table of data. Each relation consists of a set of named columns and an arbitrary number of unnamed rows

Data flow diagram (DFD)

a picture of the movement of data b/t external entities and the processes and data stores w/in a system

Economic feasability

a process of identifying the financial benefits and costs associated with a development project - often referred as cost-benefit analysis - project is reviewed after each SDLC phase in order to decide whether to continue, redirect or kill a project

Secondary normal form (2NF)

a relation is in 2NF if every nonprimary key attribute is functionally dependent on whole primary key

Third normal form (3NF)

a relation is in normal form and has no functional (transitive) dependencies b/t 2 or + nonprimary key attributes

Well structured relation

a relation that contains a minimum amount of redundancy and that allows users to insert, modify and delete the rows w/o error or inconsistencies; also known as a table

Unary relationship

a relationship b/t instances of one entity type; also called recursive relationship

Binary relationship

a relationship b/t instances of two entity types. This is the most common type of relationship encountered in data modeling

Referential integrity

a rule that states that either each foreign key must match a primary key value in another relation or the foreign key value must be null (i.e. have no value)

Repeating group

a set of 2 or + multivalued attributes that are logically related

Ternary relationship

a simultaneous relationship among instance of three entity types

Homonym

a single attribute name that's used for 2 or + different attributes

Entity instance

a single occurrence of an entity type. Also known as instance

Null value

a special value field, distinct from zero, blank, or any other value that indicates that the value for the field is missing or otherwise unknown

Joint Application Design (JAD)

a structured process in which users, managers and analysts work together for several days in a series of intensive meetings to specify or review system requirements - Purpose: collect system requirements simultaneously from key ppl - conducted off site; team members meet in isolation - result: intense and structured, but highly effective process (highly focused) - last from about 4 hrs to entire week and may consist of several sessions - started by IBM in 1970s

Subtype

a subgrouping of the entities in an entity type that is meaningful to the organization and that shares common attributes or relationship distinct from other subgroupings

Break-even analysis

a type of cost-benefit analysis to identify at what point (if ever) benefits equal cost

Triggering specialization rule

an assertion or rule that governs the validity of data manipulation operations such as insert, update, and delete; also called a trigger Includes components: - user rule: statement of business rule to be enforced by trigger - event: data manipulation operation that initiates operation - entity name: name of entity being accessed or mod - condition: condition that causes operation to be triggered - action: action taken when operation is triggered

Relationship

an association b/t instance of 1 or + entity types that is of interest to the organization

Candidate key

an attribute (or combination of attributes) that uniquely identifies each instance of entity type

Primary key

an attribute (or combination of attributes) whose value is unique all occurrences of a relation

Foreign key

an attribute that appears as a nonprimary key attribute in one relation and as a primary key attribute (or part of primary key) in another relation

Composite attribute

an attribute that has meaningful component part detailed model that captures the overall structure of organizational data that's independent of any database management system or other implementation consideration e.g.: Employee_Name(First_Name,Last_Name)

Optional attribute

an attribute that may not have a value for every entity instance e.g.: Date_of_Birth

Multivalued attribute

an attribute that may take on 1 or + than one value for each entity instance

Required attribute

an attribute that must have a value for every entity instance e.g.: Employee_ID

Derived attribute

an attribute whose value can be computed from related attribute values e.g.: [Employee_Age] *[Employee_Age] is from DOB

Associated entity

an entity type that associates the instances of 1 or + entity types and contains attributes that are peculiar to the relationship b/t those entity instances; also called gerund

Functional decomposition

an iterative process of breaking the description of the system down into finer and finer detail, which creates a set of charts in which one process on a given chart is explained in greater detail on another chart - continues until no subprocess can logically be broken down any further

Prototyping

an iterative process of systems development in which requirements that are converted to a working system that is continually revised though close collaboration b/t an analyst and users - quickly converts requirements to working version of system - once user sees requirements converted, will ask for mods or will generate additional requests

Context diagram

an overview of an organizational system that shows the system boundaries - external entities that interact w/system - major info flows b/t entities and th system *only one process symbol and no data stores shown

Attribute

A named property or characteristic of an entity that's of interest to the organization - e.g. Vehicle_ID - place its name inside rectangle for associated entity in E-R diagram