CS1004: Information Systems & Organisations (Block 1 & 2) [HL]

CS1004: Information Systems & Organisations Flashcards (Block 1 & 2)

What is a system?

A collection of non-random components that are useful, belong together and coherent

What is an open system?

It interacts with other systems by having inputs or outputs

What is a closed system?

Does not interact with their environment

What is a sub-system?

A component or unit that is part of a larger system

What is data?

A record of an event or fact

How does data become information?

Undergoes some sort of process to become useful information

What is information?

Data that is processed for a purpose

What is a information system?

A system that provides information to support decisions and business activities

What are the 3 stages in making decisions?

Intelligence, design, choice

Intelligence stage

Become aware that a problem exists that requires action

Design stage

Evaluate alternative solutions and the implications of each

Choice stage

Select choice

Structured decisions

are governed by clear rules and steps

Unstructured decisions

have no set of rules or procedure for arriving at decisions

Decision making hierarchy (bottom to top)

Supervisory, Middle, Executive

Transaction Processing Systems (TPS)

Information systems that are used at the lower level

A business process….

consists of one or more activities that are performed in a specific order

A transaction…

when a process involves different parties

Supervisory level activity

operational control e.g: product id, reorder amount, current stock level

Middle level activity

management control e.g: allocate budget, predicted resource requirements, total funding available

Executive level activity

strategic planning e.g: market research, cost of production, existing/competitors product range

Business purchase transaction process

order from factory, receive goods, pay bill

Business sales transaction process

place order, deliver goods, pay bill

Checkable data

customer info, item info, order info, staff entries

What data is needed?

data about customer, product, order

Variations that can go wrong…

wrong item or quantity entered/delivered/customer/address

Management Information System is a…

middle level

An MIS…

takes data from TPS and produces summaries and statistics

Example of a MIS summary report

is a loan needed, how long does a sale/purchase take, are we overstocking

Example of a MIS exception report

stock too low? order more. high vehicle costs? replace.

What level are DSS?

executive level

What is a DSS?

an interactive system that helps
managers with an unstructured decision

a DSS

may take data from TPS or MIS
may use models or simulations
provides reports and analysis
answers what if questions

an expert system

a system designed to mimic the decision making ability of a human expert

What is good information in an IS?

relevant, accurate, timely

What are the 5 activities of a lifecycle?

system analysis, system design, implementation, validation, maintenance

What are requirements?

something the system must do or a quality
that the system must have

What are the 2 types of requirements?

functional and non-functional

Functional requirements

what a system must do

Non-functional requirements

how a system must do it

System analysis requirements

gather requirements, analyse requirements, specify requirements, validate requirements

Role of the analyst

to understand and communicate
with clients to establish business/user needs

Statement of scope

a short concise statement of the primary function of the system
being developed that has what is and isn’t included

A use case

describes how the primary actor interacts with a system or organisation to achieve a goal

scope (not statement of scope)

the machine used in a use case

Use case structure…

primary actor, goal, scope, main sequence

Primary actor

the stakeholder/user who or which
initiates an interaction with the system in order to achieve a goal

Goal

what the actor wants to achieve in
interacting with the system

Main sequence

sequence of steps or events that
occur in a case where nothing goes wrong

Business use case

interaction between
company and client/partner

System use case

interaction between
computer system and user

A casual use case….

must have a primary actor, goal, scope and main sequence

A fully dressed use case includes more detail such as….

supporting actors, stakeholders, trigger, preconditions, guarantees

Stakeholder

something or someone with a vested interest (stake) in the behaviour or outcome of the use case

Trigger

the event that initiates the use case

Pre-conditions

what must be true before the use case can occur

Guarantees (or Postcondition)

the outcome, what must be true after the use case has occurred

Primary actor vs Stakeholder

Primary actors interact directly with the system. Stakeholders don’t necessarily interact directly but are still involved. All actors are stakeholders, but not all stakeholders are actors

A use case =

a goal

A system =

many use cases

A use case is any direct interaction with a computer system. (True or False)

False. There are also business use cases.

Use cases specify interface design. (True or False)

False. Use cases specify functional requirements.

An actor in a use case maybe not be a human. (True or False)

True. An actor doesn’t necessarily have to be a human, it can be a system.

What are extensions?

variations at each step of a sequence that considers what might go wrong/be different

How extensions work?

identify possible variations in each steps of a sequence and identify what to do to recover

Extensions within extensions

for each extension condition at each step, there needs to be an extension handling step

Extension conditions vs Extension handling

extension conditions point out what might go wrong. extension handling are the steps to recover from those conditions

Guarantees or Post Conditions

the outcomes, what must be true after the use care has occurred

Success Guarantee

if the case succeeds

Minimum Guarantee

however else the use case ends

Checking consistency

whether the entries on different parts of the use case template is internally consistent

Checking completeness

whether there is another use case that provides the relevant data for a step

What is an Entity?

A types of thing on which an organisation may wish to hold data

What is an Attribute?

The data we need to know/collect about each entity

What is the attribute domain?

The set of all possible values of an attribute

What is a Simple Attribute?

Those that cannot be further divided into sub-attributes

What is a Composite Attribute?

An attribute that is a combination of other attributes

What is a Single-valued attribute?

Only accept one value

What is a Multi-valued attribute?

An attribute that can have more than one value associated with the key of the entity

What is a Derived Attribute?

Can be derived from the values of other attributes

What is a Relationship?

How two or more entities are linked to one another

What shape is an Entity?

Rectangle

What is a Cardinality of a relationship?

How many instances of an entity relate to one instance of the other entity

Cardinality examples:

1..1, 1..*, ..

What is a primary key?

The attribute that uniquely identifies an entity

What is a foreign key?

Links attributes in other entities

What’s the relationship between primary and foreign key in a 1..* relationship?

The primary key from the “1 end” is added as foreign key in the “many end”

What’s the relationship between primary and foreign key in a 1..1 relationship?

Both ends may have the same primary key

How are relationships between entities created?

Created by keys and are represented by storing the primary key values in the other entity

What are Events?

Something that happens in the environment thus causing entities to change state

What is a State?

A recognisable period in the life of an object

Different states mean…

Different capabilities, Different constraints, Different characteristics

What shape is a state?

Rounded rectangle

What is a Guard or Guarded Transition?

Boolean expression, if it’s true the transition is allowed

What shape is the Transient State or Pseudo-state?

Diamond

What is State diagram?

Used to represent the different states of a Data Entity

What is an Activity?

An ongoing process of performing some action

What does an activity diagram show?

Ordering of activities and the transitions between them, Sequencing Use Cases

What shape is an Activity?

Rectangle with semicircle end

What shape is a Decision point?

Rotated square