SSM

1
SSM Information Systems

• Wilsons approach to defining information
  requirements from conceptual models.
• Why SSM for IS?
• How has it been applied?

2
SSM Overview
Choosing building models of relevant systems
of purposeful activity, each based on a world-view
Finding out about the problem situation,
including cultural/ political aspects

-




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

3
SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
Map activities to IPPs
(Adapted from Wilson, 1990)
4
Wilsons 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 (IPPs).
• Role - a position in the organisation. Roles are
  responsible for activities.

5
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.

6
Consensus models - comparing models

• We can compare different (primary task) models
  based on different Ws.
• One of these will be based on a neutral primary
  task description something essential that
  no-one will dispute.

7
Consensus models - agreed activities

• Take the neutral models activities
• Examine other models activities
• Add others after seeking agreement /
  accommodation
• Choose activities that give a coherent model

?
?
8
Producing the CPTM
Individual models
4 Compare test model with tentative consensus
model
Consensus PTM
(CCTA, 1993)
9
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

10
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 Ws 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.

11
SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
(Adapted from Wilson, 1990)
12
Information categories

• Information data meaning.
• Information categories are therefore not just
  data items, but are defined in a way that
  indicates how theyre used.
• E.g. Stock availability rather than quantity
• Define the data in each category
• Lower level models tend to have more detailed
  information categories.

13
Simple way to show information requirements
Available products
Purchase orders
3
Re-order goods

• What information does it require?
• What information does it produce?

Stock levels
14
Input/output table
15
SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
(Adapted from Wilson, 1990)
16
Maltese Cross
N
E
W
S
17
Maltese Cross
Check order Despatch goods
Stock levels Stock card - item no qty
Orders Order record
Stock levels Stock card - item no qty
Orders Order record
N S
E W
Item file - quantity available
Item file - quantity available
X
X
X
Sales OP
X
X
Stock ctrl
Debtors
X
Current IPPs
18
Organisational mapping

• What role is responsible for each activity?

Sales Mgr
19
Wilsons 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.

20
Wilsons 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 IPPs.)
• 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.

21
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.

22
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.

23
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.

24
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
• (Flynn, in Bennett et al. section 2.3)

25
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)

26
SSADM 4 Business Modelling

• An 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)

27
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 Ws.

28
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.

29
SSM in Business Activity Modelling

• SSM gives one possible approach based on
  Wilsons 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)
30
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

31
Link to Work Practice

• CPTM 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

32
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)

33
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)

34
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.

35
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

36
In these two weeks, we have

• Learned the structure and techniques of SSM
• Seen how to map SSM models onto information
  requirements using Wilsons approach
• Seen, briefly, some other uses of SSM in the IS
  field
• Discussed why we might want to do this.

37
Follow-up preparation

• Finish workbook (if you havent)
• Prepare for seminar section 7 of workbook
• Further reading as specified in workbook, and dip
  into the items on Wilsons approach.

38
References Further Reading

• On Wilsons 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 

39
References/Bibliography

• Wilsons 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.

40
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.

41
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