Information Modelling

What is information system? (System Analysis and Design Method, Whitten, Bentley, Dittman, McGrow-Hill, 5th edition)

What is methodology? What is technique? What is tool?

framework for comparison of information systems development methodologies

Review of the BookInformation Systems Development Methodologies,

Techniques, and ToolsDavid Avison, Guy Fitzgerald

4th edition McGrow-Hill

2008

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Information Systems & TechnologyAn information system (IS) is an arrangement of

people, data, processes, communications, and information technology that interact to support and improve day-to-day operations in a business, as well as support the problem-solving and decision-making needs of management and users.

Information technology is a contemporary term that describes the combination of computer technology (hardware and software) with telecommunications technology (data, image, and voice networks).

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Information Systems Architecture

Information systems architecture provides a unifying framework into which various people with different perspectives can organize and view the fundamental building blocks of information systems.

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Information System Building Blocks

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Perspectives or Stakeholders System owners pay for the system to be built and

maintained. System users use the system to perform or support

the work to be completed. System designers design the system to meet the

users’ requirements. System builders construct, test, and deliver the

system into operation. Systems analysts facilitate the development of

information systems and computer applications by bridging the communications gap that exists between nontechnical system owners and users and technical system designers and builders.

IT vendors and consultants sell hardware, software, and services to businesses for incorporation into their information systems.

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Focuses for Information Systems

Data—the raw material used to create useful information.

Processes—the activities (including management) that carry out the mission of the business.

Interfaces—how the system interfaces with its users and other information systems.

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Front- and Back-Office Information Systems

Front-office information systems support business functions that reach out to customers (or constituents). Marketing Sales Customer management

Back-office information systems support internal business operations and interact with suppliers (of materials, equipment, supplies, and services). Human resources Financial management Manufacturing Inventory control

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A Federation of Information Systems

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Classes of Information SystemsTransaction processing systemsManagement information systemsDecision support systemsExpert systemsOffice automation systems

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Transaction ProcessingTransaction processing systems are information system applications that capture and process data about business transactions.

Includes data maintenance, which provides for custodial updates to stored data.

Business process redesign (BPR) is the study, analysis, and redesign of fundamental business (transaction) processes to reduce costs and/or improve value added to the business.

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Management Information Systems

A management information system (MIS) is an information system application that provides for management-oriented reporting. These reports are usually generated on a predetermined schedule and appear in a prearranged format.

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Decision Support SystemsA decision support system (DSS) is an information system application that provides its users with decision-oriented information whenever a decision-making situation arises. When applied to executive managers, these systems are sometimes called executive information systems (EIS).

A data warehouse is a read-only, informational database that is populated with detailed, summary, and exception data and information generated by other transaction and management information systems. The data warehouse can then be accessed by end-users and managers with DSS tools that generate a virtually limitless variety of information in support of unstructured decisions.

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Expert SystemsAn expert system is a programmed decision-making information system that captures and reproduces the knowledge and expertise of an expert problem solver or decision maker and then simulates the “thinking” or “actions” of that expert.

Expert systems are implemented with artificial intelligence technology that captures, stores, and provides access to the reasoning of the experts.

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Office Automation SystemsOffice automation (OA) systems support the wide range of business office activities that provide for improved work flow and communications between workers, regardless of whether or not those workers are located in the same office.

Personal information systems are those designed to meet the needs of a single user. They are designed to boost an individual’s productivity.

Work group information systems are those designed to meet the needs of a work group. They are designed to boost the group’s productivity.

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Information Systems Applications

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Methodologies

A collection of procedures, techniques, tools, and documentation aids which will help the system developers in their efforts to implement a new information system. A methodology will consists of phases, themselves consisting of sub phases, which will guide the systems developers in their choice of the techniques that might be appropriate at each stage of the project and also help them plan, manage, control, and evaluate information systems projects. (25 different metthodologies)

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Avison & Taylor identified 5 classes of situation and appropriate approaches:

Class 1: well-structured, defined problems, clear requirements

Class 2: as above but unclear requirements

Class 3: unstructured, unclear objectives

Class 4: high user-interaction systems

Class 5: very unclear situations

traditional methodology (SSADM)

data or process model (JSD or STRADIS)

soft systems approach (SSM)

a people-focussed, like ETHICS

a contingency approach (Multiview)

However:

methodologies are NOT stable

there are a variety of versions out there

and practice is often different to that prescribed

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1. Philosophy• Paradigm• Objectives• Domain• Target

2. Model

3. Techniques and tools

4. Scope

5. Outputs

6. Practice• Background• User base• Players

7. Product

Avison & Fitzgerald’s framework for comparison of information systems

development methodologies:

SPEED?QUANTITY?USER MODIFICATION?

not addressed

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Philosophy:distinguishes a “method” from a “methodology”

may be explicit but in most methodologies is implicit

a set of principles that underlie the methodology

NOT just wishing to improve the world of information systems development

this is perhaps the most important aspect when comparing methodologies - nearly ALL the features are highly dependent upon the philosophy and without this understanding, the methodology is difficult to explain

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Philosophy:• paradigm

a specific way of thinking about problems

science systems“reduce the complexity of the variety of the real world in experiments whose results are validated by their repeatability, and thereby build knowledge by the refutation of hypotheses”

implies that breaking things down into smaller parts does not disrupt the system

“Checkland argues that human activity systems … do not display such characteristics, they have emergent properties (that is the whole is greater than the sum of the parts)”

systems paradigm concern is with the whole picture, the emergent properties and inter-relationships

HARD SOFTTHINKING

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Philosophy:• paradigm

the theory of knowledgethe study of the nature and essence of things

ONTOLOGY EPISTEMOLOGY

Positivism InterpretivismRealism Nominalism

EPISTEMOLOGY

ONTOLOGY

Positivism

Interpretivism

Realism Nominalism

ObjectivistApproaches

SubjectivistApproaches

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“postulates that the universe comprises objectively given, immutable objects and structures. These exist as empirical entities, on their own, independent of the observer’s appreciation of them”

“reality is not a given immutable ‘out there’, but is socially constructed. It is the product of the human mind. Social relativism is the paradigm adopted for understanding social phenomena and is primarily involved in explaining... the social process of reality construction”

Realism

Nominalism

implies the existence of causal relationships which can be investigated using scientific method

Positivism

implies there is no single truth that can be “proven” by such investigation. Different views and interpretations are potentially legitimate and the way to progress is not to try and discover the one “correct” view but to accept the differences and seek to gain insight by a deep understanding of such complexity.

Interpretivism

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largely embodied in techniques such as entity relationship modelling or data flow diagrams

most areas involving people’s lives;may include “facts”, like sales targets which are negotiated

Objectivist:

Subjectist:

ObjectivistApproaches

SubjectivistApproaches

it is clear SSM adopts the systems paradigm - the subjectivist approach. The participative approach of ETHICS analyses the work system without decomposition.

“the only way to solve complex problems is to divide them into sub-problems until they become manageable. A requirement for this to work is that the solution to the sub-problems gives the solution for the problem as a whole, that is, that the division in sub-problems is coherent.”

STRADIS, YSM, IE, SSADM, Merise, JSD, OOA are all reductionist, accept the ontological position of realism and so firmly belong in the science paradigm

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Philosophy:• objectives• domain• target

determines the boundaries of the area of concern

“the problem with concentrating only on aspects to be computerised is that this is an artificial boundary in terms of the logic of the business. There is no reason why the solution to a particular problem should reside only in the area that can be automated.”

in choosing and understanding a methodology, it might be a good idea to ask the question: “could the use of this methodology lead to the implementation of a purely organisational or manual solution?”

It is interesting to note that most of the widely-used commercial methodologies would give “No”, whereas most academic methodologies would probably give “Yes”, excepting BPR.

automation

the organisation

Is it aimed at particular types of application, types of problem, size of system or environment?

what is the reality of the methodology being “general purpose”?

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Different assumptions A system that:Makes most ust of computers is a good

solution.Produces the most appropriate

documentation is a good solution.Is the cheapest to run is a good solution.Is implemented earliest is a good solutionIs the most adaptable is a good solution.That makes the best use of the techniques

and tools available is a good solution.That is liked by the stakeholders is a good

solution.

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Types of Methodologies1- Process Oriented: Structured analysis, design and implementation of

information systems (STRADIS) Yourdon Systems Method (YSM) Jackson Systems Development (JSD)2- Blended: Structured Systems Analysis and Design Method

(SSADM) Merise Information Engineering Welti ERP Development

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Types of Methodologies3- Object – Oriented:• Object-oriented analysis (OOA)• Rational Unified Process (RUP)4- Rapid Development:• James Martin’s RAD• Dynamic Systems Development Method (DSDM)• Extreme Programming (XP)• Web Information Systems Development Methodology

(WISDM)

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Types of Methodologies5- People – Oriented:• Effective Technical and Human Implementation of Computer-

based Systems (ETHICS)• KADS• CommonKADS6- Organizational oriented:• Soft Systems Methodology (SSM)• Information Systems Work and Analysis of Change (ISAC)• Process Innovation (PI)• Projects in Controlled Environments (PRINCE)• Renaissance7- Frameworks• Multiview• Strategic Options Development and Analysis (SODA)• Capability Maturity Model (CMM)• Euromethod

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TechniqueIs a way of doing a particular activity in the

information systems development process, and any particular methodology may recommend techniques to carry out many of these activities. (29 different techniques)

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Types of Techniques1- Holistic: Rich pictures Root definitions Conceptual Models Cognitive Mapping2-Data: Entity Modelling Normalization3-Process: Data Flow Diagramming Decision Tree Decision Tables Structured English Structure Diagrams Structured Walkthroughs Matrices Action Diagram Entity Life Cycle

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Types of Techniques4- Object Oriented: Object Orientation Unified Modeling Language (UML)5-Project Management Estimation Techniques PERT Charts Gantt Charts6-Process: Lateral Thinking Critical Success Factors (CSFs) Scenario Planning Future Analysis Strengths, Weaknesses, Opportunities, and Threats Analysis

(SWOT) Case – based Reasoning Risk Analysis7- People: Stakeholder Analysis Joint Application Development

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Model:basis of the methodology’s view of the

world - an abstraction

• Verbal• Analytic• Iconic• Simulation

4 categories of models:

IS methodology models of this type

this dominance is because of the perceived importance of communication between users and analysts

abstraction:stripping an idea or a system of its concrete or physical features - provides a way of viewing important aspects of the system at various levels

the “essence”

the detailwithout

compromise

“the process of abstraction loses information and so a model should only lose that information which is not part of the “essence” of the system.”

Abstraction is closely related to hierarchical decomposition. “Natural” levels of decomposition, are

• conceptual• logical• physical

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“Natural” levels of decomposition:

• conceptual• logical• physical

Concept: “…the definition of the problem structure of an IS, like a map defines the problem structure of a transport system.”

a description of the universe of discourse

Logical level: a description of the IS without any reference to the technology that could be used to implement it - its scope is the IS itself not the UoD

mainly to provide requirements specification of the IS

Physical level: a description of the IS including the technology of the particular implementation

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Tools:

Project management tools: Microsoft ProjectDatabase management systems: ACCESSDrawing tools: Microsoft VisioCASE tools:Power Designer, Rational RoseWebsite Development: DreamweaverGroupware: GroupSystems

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Techniques & Tools:

many methodologies include techniques as part of them- STRADIS, YSM, SSADM and JSD

some, like ISAC, do not rely on particular techniques

some, like IE, explicitly suggest that techniques are not a fundamental part of the methodology and that recommended techniques can be replaced as better ones come along

SSADM, Merise and IE stress a separation between data and processes so these methodologies would not fit well with an object-oriented modelling technique which integrates the two

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Techniques & Tools:

SSM does not even MENTION tools, let alone recommend the use of particular ones. However, many methodologies do - YSM, IE, SSADM, Merise, JSD, OOA and Process Innovation

they range from simple drawing tools to those which support the whole development process, including prototyping, project management and code generation

IE, like RAD, suggest developments shouldn’t proceed with the use of tools

SSADM and OOA suggest tools are helpful but not essential

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STR

AD

IS

YSM

IE SS

AD

M

Meri

se

JSD

OO

A

ISA

C

ETH

ICS

SS

M

PI

StrategyFeasibility

AnalysisLogical design

Physical designProgramming

TestingImplementation

EvaluationMaintenance

SCOPE OF METHODOLOGIES

Strategy is used to indicate any aspects which relate to organisation-wide context and deals with overall IS strategy, purpose and planning

Comparisons do not include Multiview (a combinational methodology), RAD (similar to IE), KADS (applied to expert systems only) or Euromethod (simply a framework)

Scope:

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Outputs: Can vary from being an analysis specification to a working implementation of the system

Can be considerable variation not only in terms of what should be produced but also in the level of detail that the methodology specifies

Related to whether the methodology is a:

“blueprint” for action

“framework” within which analyst has much discretion

outputs also help “direct” the analyst - let them know that they are proceeding correctlysome outputs may be described in great details but not how to generate them viz. ISAC’s analysis of change using A-graphs

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Practice:• background• user base• players

Origins?

the use of the methodology

commercial

academic

Vendors would have you believe anyone who enquired about the methodology was actively using it!

Wasserman et al (1983). Characteristics of software development methodologies. In: Olle et al. (1983). Information systems design methodologies: A feature analysis. Pub. North Holland, Amsterdam.

Of 24 methodologies investigated nearly half had been used in 10 or fewer projects

Informatics survey of ~60 users in 1990:

19 SSADM12 JSD 9 IE 8 YSM11 in-house

In France Merise is used in between 20-61% of cases

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Practice:• background• user base• players

Who is supposedly involved with the use of the methodology?

What roles do they perform?

traditional view is that of a specialist team of professional systems analysts and designers + professional programmers - STRADIS, YSM, IE, SSADM, Merise, JSD and OOA

SSM, ISAC, PI and ETHICS have a different view: users have a more proactive role

in ETHICS the users themselves perform the analysis and design and consultants are used when required and a facilitators are central to the methodology

some level of skill is always required

Some methodologies also require considerable user skills

but training may not be explicitly included for users - ETHICS does so

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Product:What is supplied when purchasing a

methodology?

likely to be a “minimum set”

with extras: add-ins

maybe a large set of manuals, the recipes, like SSADM or a set of academic articles,

like SSM

some come with certificated training courses, consultants and facilitators

• Software• development support tools• written documentation• agreed number of training hours• telephone help service• consultancy