Title: SSM
1SSM Information Systems
- Wilsons approach to defining information
requirements from conceptual models. - Why SSM for IS?
- How has it been applied?
2SSM 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
3SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
Map activities to IPPs
(Adapted from Wilson, 1990)
4Wilsons 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.
5Consensus 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.
6Consensus 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.
7Consensus 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
?
?
8Producing the CPTM
Individual models
4 Compare test model with tentative consensus
model
Consensus PTM
(CCTA, 1993)
9Other 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
10Consensus 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.
11SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
(Adapted from Wilson, 1990)
12Information 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.
13Simple 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
14Input/output table
15SSM for IS definition based on Wilsons approach
To design
Map to organisation (role-role flows)
(Adapted from Wilson, 1990)
16Maltese Cross
N
E
W
S
17Maltese 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
18Organisational mapping
- What role is responsible for each activity?
Sales Mgr
19Wilsons 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.
20Wilsons 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.
21Rationale (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.
22Rationale (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.
23Rationale (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.
24Causes 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)
25Causes 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)
26SSADM 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)
27Business 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.
28Logical 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.
29SSM 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)
30Link 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
31Link 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
32SSM 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)
33SSM 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)
34SSM 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.
35SSM 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
36In 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.
37Follow-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.
38References 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
39References/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.
40References/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.
41References
- 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