SSM & Information Systems Wilson’s approach to defining information requirements from conceptual models. Why SSM for IS? How has it been applied?

SSM & Information Systems

Wilson’s approach to defining information requirements from conceptual models.

Why SSM for IS? How has it been applied?

SSM Overview

-

Finding out about the problem situation, including cultural/ political aspects

Choosing & building models of “relevant systems” of purposeful activity, each based on a world-

view

Taking action to improve ...

Debate the situation using the models (Comparison)

- Identify systemically desirable and culturally feasible changes

-Find accommodations between conflicting interests that will enable …

Understanding of the organisation,

including cultural and political

analysis

SSM for IS definition: based on Wilson’s approach

Find out about the problem situation

Root definitions

Conceptualmodels

Compare models with real world

Map toorganisation(role-roleflows)

Map activitiesto IPP’s

Defineinformationcategories

Defineactivity-activityflows

Todesign

(Adapted from Wilson, 1990)

FormCPTM

MalteseCross

Wilson’s approach - definitions CPTM - Consensus Primary Task Model. IPP = Information processing procedure

- a current information system, automated or manual.

Maltese Cross - matrix technique for comparing information requirements of CPTM with real world information provision (IPP’s).

Role - a position in the organisation. Roles are responsible for activities.

Consensus Primary Task Model (CPTM)

“What we are taking the organisation business processes to be.” (Wilson, 2001)

Still a Conceptual Model! “The consensus of the problem-

solving group that this is what they are taking the organisation unit to be doing (now or in the future).” (Wilson, 2001)

Various ways of producing this model.

Consensus models - comparing models

We can compare different (primary task) models based on different W’s.

One of these will be based on a neutral primary task description – something essential that no-one will dispute.

Consensus models - agreed activities

Take the neutral model’s activities

Examine other models’ activities

Add others after seeking agreement / accommodation

Choose activities that give a coherent model

Neutral model

100% consensus

Local consensus

Producing the CPTM

1 Produce initialCPTM from individualmodels

2 Derive RD from model

3 Derive test modelfrom RD

5 Modify RD and/or model(s)

4 Compare testmodel with tentativeconsensus modelConsensus PTM

Individualmodels

(CCTA, 1993)

Other ways of producing CPTM

Model the Mission Statement Already agreed Sometimes vague, seen as irrelevant, etc.

Extract it from a model of a wider system If you have one May be difficult to get a definable system from

the gaps Assemble it from smaller models

Within a general framework for organisations in system terms, into which they can fit – Wilson (2001) provides one

Consensus models - do we need them?

We now have an agreed model - a consensus primary task model

Often regarded as essential precursor to defining information requirements

Why?

CPTM takes W’s into account when forming the model.

Some analysts believe that the variety of viewpoints should be preserved in information definition by continuing with multiple models.

SSM for IS definition: based on Wilson’s approach

Find out about the problem situation

Root definitions

Conceptualmodels

Compare models with real world

Map toorganisation(role-roleflows)

Map activitiesto IPP’s

Defineinformationcategories

Defineactivity-activityflows

Todesign

(Adapted from Wilson, 1990)

FormCPTM

Information categories

“Information = data + meaning.” Information categories are therefore not

just data items, but are defined in a way that indicates how they’re used. E.g. “Stock availability” rather than

“quantity” Define the data in each category Lower level models tend to have more

detailed information categories.

Simple way to show information requirements

Re-order goods

Available products

Stock levels

Purchase orders3

What information does it require?

What information does it produce?

Input/output tableActivity Reorder goods Despatch

Order Receive delivery

Inputs Available products, Stock levels

Orders, Stock levels, Carrier availability

Delivery,

Outputs Purchase orders

Despatches Receipt, Rejection

Measures of performance

Stockouts Turnaround time

SSM for IS definition: based on Wilson’s approach

Find out about the problem situation

Root definitions

Conceptualmodels

Compare models with real world

Map toorganisation(role-roleflows)

Map activitiesto IPP’s

Defineinformationcategories

Defineactivity-activityflows

Todesign

(Adapted from Wilson, 1990)

FormCPTM

Maltese Cross

NW E

S

InputICs

OutputICs

IC1IC2IC3IC4IC5IC6 IC6IC5IC4IC3IC2IC1

Do...

Store...

Find...

Issue...

Activities from model

IPPs

Sales OP

Stock ctrl

Debtors

X

X

X

X

X

X

X

X

X X

XX

X X

X

X

Maltese Cross

InputICs

OutputICs

Data structures

Data structures

Current IPPs

Sales OP

Stock ctrl

Debtors

XX

X X

X

Stocklevels

Stock card - item no & qty

Orders

Order record

Item file -quantity available

X

Check order Despatch

goods

Stocklevels

Stock card - item no & qty

Item file -quantity available

Orders

Order record

N

S

E W

Organisational mapping What role is responsible for each activity?

1

842

3 5

7

6

?Marketingasst

MD

Sales Mgr

SalesMgr

Salesperson

Accountsclerk

Sales-person

Sales Mgr

Sales

Marketing

Accounts

Wilson’s approach – summary (for you to read)

Derive primary task model(s) and gain consensus about these. (“Consensus primary task model”)

Derive the categories of information (sets of “data + meaning”) needed to support the activities, and the information categories produced by activities. Enter the categories into both East and West sides of a Maltese Cross, representing output and input.

Create the NW and NE matrices, relating the categories to the activities which will use and create them.

Wilson’s approach - summary (2)

Take each existing Information Processing Procedure (IPP) and identify the information categories to which the input and output data belong. This gives the bottom half of the Maltese Cross.

Using the Maltese Cross, identify omissions, duplications etc. and define any necessary additional processes, avoiding duplication. (Wilson now does activity models of these new/changed IPP’s.)

Define management roles in terms of the activities for which each manager is decision-taker. Convert the “activity to activity” information flows into “role to role” information flows.

Rationale (1)

“Systems analysis aimed at information systems design, if it is to make much impact, must first concentrate on the activity system which the information system is to serve.” (Checkland, Systems Thinking, Systems Practice)

So, we conceptualise the activity (served) system before the information (serving) system.

Rationale (2) Data is not information. Information

involves attributing meaning, and can then inform action.

IS provide knowledge to support purposeful activities - hence people need to attribute meaning to the data, otherwise we just have a “data manipulation system”.

We need to understand what meaning people will give to data - hence useful to examine viewpoints, political factors etc.

Rationale (3) The activity system must contain activities

which are feasible and seen as meaningful, and form a consistent whole.

We need to understand the organisational situation & the environment - a “rich understanding” is provided by SSM

We need to agree what this consistent, feasible & meaningful activity system consists of - SSM gives us a way to do this.

Causes of IS failure•The wrong problem is addressed•Wider influences are neglected•Analysis is carried out incorrectly•Project undertaken for wrong reason•Users change their minds•External events change the environment•Implementation is not feasible•Poor project control

(See Bennett et al. section 2.3)

SSADM 4+ Business ModellingAn optional precursor to SSADM. Includes: Business Activity Modelling

Business Perspectives (why) Logical activity (what) Business events (when) Business Rules (how)

Work Practice Model User roles (who) Organisation structure & geography (where)

(See SSADM 4+ User Guide)

Business Activity Modelling Business Perspectives

What the business is trying to achieve “To be a high-quality eco-tourism provider

catering for niche markets” May be several, sometimes conflicting Used as basis for critical success factors,

measures of performance Sounds familiar? Could be root definitions, perhaps

several based on different W’s.

Logical Activity Model Business activities that must be carried

out and the dependencies between them Modelled with control systems, feedback

etc.

Sounds familiar? Could be conceptual models, especially

CPTM.

SSM in Business Activity Modelling

SSM gives one possible approach – based on Wilson’s techniques

Create root definitions (Business perspectives included)

Derive Primary Task Models for essential activities

Derive Consensus Model “Test against reality”

The RD is “What they believe their business to be.”(SSADM4+ User Guide)

Link to requirements Extract functional requirements from CPTM

Requirements Catalogue Convert CPTM to required system Data Flow

Model Define external entities Convert activities to processes within or outside

system boundary (decompose?) Identify information support where activities are

outside boundary, & define system functions to provide it

Specify performance modelling data Define data stores

Link to Work PracticeCPTM contributes to Work Practice

Model Identify activities that could be

automated Map onto organisation structure and

geography User roles Locations May need to decompose activities

SSM in SSADM feasibility

SSM may be used before a feasibility study instead of a feasibility study as part of a feasibility study

Detailed guidance published (CCTA, 1993)

SSM deliverables in SSADM Feasibility

Help define the scope of the study (rich picture) Suggest/confirm key entities for data model (RD) Help decide what current systems analysis to do (RD, CM) Identify functional & non-functional requirements (RD, CM, CPTM) Identify & scope feasibility options (CM, Maltese Cross) Identify information requirements & gaps in existing provision

(Maltese cross, Information activity table) Identify users Help produce & check data flow models (CPTM, information

categories) Identify service levels and management information (measures of

performance)

SSM has also been used with…

UML – linked to use cases or activity diagrams Other OO methods, (Schlaer-Mellor, Galvin & Lane

(1999)) DFDs – several attempts (see Mingers, 1995) Multiview – a method for small systems, with an SSM-

based first phase. Also Multiview 2 – OO. LOTOS (formal method) JSD (Pre-OO method) Information Engineering (for strategy planning) Prototyping etc.

SSM & IS – summary of uses

In information strategy planning To decide what systems should be

built As an aid to scoping systems In a feasibility study - or instead of

one For finding information requirements To aid acceptance of systems Dealing with IS-related problems

In these two weeks, we have Learned the structure and techniques of

SSM Seen how to map SSM models onto

information requirements using Wilson’s approach

Seen, briefly, some other uses of SSM in the IS field

Discussed why we might want to do this.

Follow-up & preparation Finish workbook (if you haven’t) Prepare for seminar – section 7 of

workbook Further reading as specified in

workbook, and dip into the items on Wilson’s approach.

References & Further Reading

On Wilson’s approach –any of these is a good start. Wilson, (1990), Systems: Concepts, Methodologies, and

Applications, 2nd edn. Wiley. Chapter 6. (Or pp. 193-247 1st edn.)

CCTA (1993) Applying Soft Systems Methodology to an SSADM Feasibility Study, London: HMSO. Chapter 4.

Grant, K & Stansfield, M, “Matching Technology with Organisational Needs: Bridging the Systems Thinking Paradigm – A Practical Approach.” http://floti.bell.ac.uk/kevingrant/paper2.htm 

References/Bibliography Wilson’s approach

B. Wilson (2001), Soft Systems Methodology: Conceptual Model Building and its contribution, Wiley.

Overview of the field inc. Wilson, DFD. J. Mingers (1995), ch. 2 in F. Stowell (ed),

Information Systems Provision: the Contribution of Soft Systems Methodology, McGraw-Hill.

On rationale for using SSM for IS M.C. Winter, D.H. Brown & P.B.Checkland (1995),

“A role for soft systems methodology in information systems development,” European Journal of Information Systems 4, pp. 130-142.

References/Bibliography SSADM

CCTA (1993) Applying Soft Systems Methodology to an SSADM Feasibility Study, London: HMSO. Chapter 4. (Reference book in library)

CCTA (1995), SSADM 4+ User Guide, NCC Blackwell Multiview

D. E. Avison & G. Fitzgerald (1995), Information Systems Development: Methodologies, Techniques and Tools, McGraw-Hill. Section 6.2.

D.E. Avison & T. Wood-Harper (1990), Multiview, An exploration in Information Systems Development, McGraw-Hill.

References On Failure

Bennett, McRobb & Farmer, Object-Oriented Systems Analysis and Design using UML, McGraw-Hill. Section 2.3 (both editions)

OO approach Lane, K. & Galvin, C. (1999) “Methods for Transitioning

from Soft Systems Methodology (SSM) Models to Object Oriented Analysis (OOA), developed to support the Army Operational Architecture (AOA) and an Example of its Application.”

http://www.dodccrp.org/1999CCRTS/pdf_files/track_6/092galvi.pdf [Viewed October 04]