See "Advanced Systems Thinking, Engineering and Management," and "Putting Systems to Work," both by the author.
See also an INCOSE Tutorial, using RSM to Explore a National Nuclear Energy/Power IssueProblems come in many forms. Some, a very few, are of the type to which there is a correct, mathematical or scientific answer. Most, and the kind this section will address, are complex, multifaceted, and difficult to understand and analyze, let alone solve. Social and cultural problems are of this second kind. If a solution is supposedly found, then chances are that it will prove difficult to prove that the solution, if applied, will be guaranteed to solve the problem. And the problem is constantly changing.
It is in the nature of complex problems that they generally emerge from dynamic situations, so that potential solutions, to be effective, must be both dynamic and applied at the appropriate moment. The right solution at the wrong time will not work. Worse, it may exacerbate the issue and create distrust of the problem solving method/approach.
It gets worse! If a complex problem is multifaceted, then it is likely that any solution will be multifaceted, too. Human nature encourages problem solvers, once they have identified a plethora of problem facets, to prioritize and address (what they see as) the more important aspects first. Unfortunately, this often fails, as the many aspects must be addressed at the same time, else the problem simply changes nature and emerges in an altered form. This is an example of counterintuitive behavior, common in real-world, complex situations. See Forrester, J.W. (1972) Understanding the Counterintuitive Behavior of Systems, Systems Behavior, Paul Chapman Publishing
The Rigorous Soft Method (RSM):
The figure above shows the method at high level, as a seven-step process. Each step invokes the use of particular techniques that are so chosen that the output from one technique forms the input required by the following technique. This moves the process forward. Each technique may also have an associated tool, perhaps to accommodate and handle information, perhaps to simulate/model developing systems and interactions.
Step 1. Nominate Issue and Issue Domain. It is helpful to avoid being too specific in naming the Issue. The Issue domain is the broad subject, area, region, category, etc., in which the Issue resides. In practice, it is sometimes necessary to enlarge the domain once the symptoms have been elicited
Step 2. Identify Symptoms and Factors. Symptoms are discernible changes from a previously satisfactory state. Factors are evident contributors to, or existing within, the Issue
Step 3. Generate Implicit Systems. Each symptom and factor implies that an imbalance has arisen between previously balanced systems. These are Implicit Systems
Step 4. Group into Containing Systems, Implicit systems are mutually related, since they form part of the same, overall Issue. Grouping the Implicit Systems, to form Containing Systems simplifies the Issue and moves the process to a higher level.
Step 5. Understand Containing System Interactions, Imbalances. Examine, model, the static and dynamic behavior of the Containing Systems
Step 6. Propose Containing System Imbalance Resolution. The Containing Systems and Interactions have captured the overall issue both at macro and at micro levels. Using the model as a guide, propose optional approaches to solve/resolve/dissolve the whole Issue. Trade off between the options by judging which addresses the imbalances and shortfalls most effectively.
Step 7. Verify Proposals against Original Symptoms. An accounting process to ensure all the original symptoms have been addressed.
The figure above, then, summarizes the RSM, but there is rather more to it.
N.B. RSM was formerly known as the Hierarchical Issue Method (HIM), and is so referred to in "Putting Systems to Work."
Before going into the RSM method, it is useful to understand the kinds of issues or problems that RSM might be used to address.
This last bullet indicates why a method for addressing issues is so important. Those making difficult and important decisions need rational advice and support. They may choose to do something quite different, but at least that choice is made in the light of good knowledge
RSM is made up from a number of simple techniques strung together. The choice of techniques is crucial to resolve vague issues
Each of the techniques is useful on its own, and may be used in other contexts. Strung together in the correct order, they provide a powerful suite of techniques for addressing the most complex of issues rigorously. Other techniques can be plugged-in, with care, e.g. Nominal Group Technique, particularly to assist with eliciting and structuring the issue symptoms at the start of the RSM process.
Warnings
Systems models are simple, yet powerful ways to organize information and perceive relationships. Perhaps the simplest system idea is that systems are made up of other systems.
The figure below - often called the poached-egg model - shows the first system model, defining hierarchy, relationship, containment, environment, etc. A System of Interest is seen at bottom right, containing 3 intra-connected subsystems within a contained environment. The System of Interest (SOI) has 3 sibling systems, i.e. they are at the same level of hierarchy and within the same Containing System. All 4 siblings are interconnected, directly or indirectly through another sibling. They coexist within an Operating Environment. The Containing System exists itself within a wider environment, and is interconnected to other Containing Systems, not shown.
Organizing things, or information about things, into systems diagrams greatly reduces perceived complexity and may, in some cases, even be sufficient to resolve an Issue.

A hard view of the world places any system uniquely in one Containing System.
On the other hand, a soft view of the world allows "simultaneous multiple containment" in more than one Container. For example, a bus driver driving a bus may be contained within,
Any or all of these Containers may influence the bus driver's thoughts and actions.
The figure below shows a developed view of the rigorous Soft Method using the terms from the poached egg model.
The underlying reason why RSM works can be explained by analogy to the way in which a doctor diagnoses patient illnesses. If a patient feels out of sorts, but has no specific idea of what is wrong, the doctor faces a dilemma. The human body is extremely complex, with many interconnected and interacting organs, so that symptoms often occur where the problem isn't (sic!). Moreover individual symptoms may have a plethora of possible causes. Spots on the chest could indicate heat rash, food poisoning, an infection, allergic reaction to some unguent, and so on. How does the doctor sort things out?
A visit to the doctor might go something like this:
"Doc, I don't know what's wrong, but I feel out of sorts"
The doctor looks for symptoms
The greater the variety of symptoms, the greater prospect of accurate diagnosis
One way in which the doctor might work is as follows
Hence diagnosis emerges, not from one symptom, but from many. The more symptoms, the more likely is it that a sound diagnosis and treatment will Emerge.
RSM operates on similar lines. Essentially, each symptom emanates from a different problem space within the overall Issue Space. Several symptoms indicate different problem spaces, some of which may overlap. The more symptoms, the more refined and confirmed becomes the area of overlap, indicating the validity of the diagnosis. In keeping with the diagnostic analogy, symptoms are considered to result from imbalances between "organs", or implicit systems
Implicit systems, those implied by symptoms, may exist in practice, but need be neither tangible nor coincident with an organizational boundary. For example
Related implicit systems are implied by the symptom
Practice shows that starting the description of an implicit system with the words: "A system for" results in a useful, soft description of a purposeful/purposive system
Symptoms are indications of change from a previous, supposedly satisfactory state
Symptoms can be found by:
Some symptoms arise from lack of cooperation (synergy) between the various people/parts in a complex system where, perhaps, cooperation previously existed. Lack of cooperation may extend to antagonism.
Other symptoms arise from culture - people caught in the trap of their experience, unable/unwilling to see other viewpoints
The figure below shows why working from individual symptoms to causes may prove difficult, as any doctor will confirm. At the left of the figure are two diagrams indicating that, when systems provide outflows to other systems, changes in the upstream system reveal themselves, not at source, but in the downstream system.
The diagram at the right shows graphically that, with a set of interconnected systems, it is possible for the symptom to emerge just about anywhere. Diagnosis difficulty is compounded when it is realized that the diagram represents a dynamic system, with all the inflows and outflows varying continually even when there is no problem.
Scientists and engineers diagnose faults by isolating each expected subsystem, feeding test inputs and checking for expected outputs. In the real social and political world, it is not possible to isolate, to stop the action and perform tests. Diagnoses have to be made on the fly during live action.

As the figure indicates, symptoms often occur where the problem isn't
Symptoms arise due to an imbalance between previously balanced system pairs:
One symptom may arise from several causes/imbalances
Symptom categories emerge according to question posed.
Responses convert to symptoms
Popular in Japan - ask why up to five times
Real causes of inefficiency:
For any given symptom there may be several potential causes - generally, it is impossible to be sure. It is important, therefore, to identify all possible causes, treat all as suspect - hence, there is a "locus of possible causes" within which the real cause(s) must lie.
This suggests that there may be redundant information in the process: later RSM steps will sort probables from possibles.
Causal Loop Modeling is a powerful technique with uses beyond RSM. However, within RSM, CLM has three main rôles

The two figures show a Laundry List example. If asked, what is the cause of perspiration. Most people would produce a list of possible causes, referred to as a "laundry list." As the figure indicates, the possible causes may not be mutually independent - we are missing something
Because the causal factors for perspiration are not independent, their relationship may be identified and used to form Figure 9. Seeing the relationships can add greatly to understanding. Given the causal loop model, we may even be able to answer questions:
Q. Should a marathon runner about to run in a humid climate drink more or less water than usual?
A. From the CLM, higher humidity means less evaporation, i.e. more sweat lost as droplets without extracting latent heat of evaporation (vaporization). Hence the marathon runner will need more water in the humid environment, since some of the body water lost to perspiration is unable to do its job of cooling the body.
Causal loop models are straightforward to produce, provided simple rules are observed:
1. Identify the symptom
2. Establish a Laundry List of contributing factors, including organizational, technological, cultural, political, economic, etc., according to Issue
3. Develop a series of simple CLMs combining contributing factors, using nouns or noun phrases only and dropping any features from the Laundry List which suggest bias, such as 'low', 'heavy', 'poor', 'hot', etc.
4. Integrate the set of simple CLMs into a fuller single version, including the Entity to be modeled.
Difficulty may arise if, instead of starting with several simple loops, the novice tries to combine all factors in a single loop from a standing start.
Causal Loop Models are all very well but they have limits. For instance:
Sometimes it is helpful to dig deeper
iThink/STELLA is a convenient tool for next-level analysis - there are may others
The figure presents an analysis of the archetypal control CLM. The Stella version of the CLM is shown at top right. It consists of two reservoirs, one each for Resources and Performance Level; the assumption must be that applying a remedy invokes the use of some resource. In the STELLA model, the gap is represented as a difference between some desired performance level and the level in the Performance reservoir as it rises, drawing upon Resources via some (resource) Allocation Rate, which is proportional to the Gap.
The graph at the bottom of the figure may seem surprisingly complicated. The reason for this is that the large initial gap causes the Resources to run dry. As Resources are replenished from some external source, they are instantly allocated to Performance Level, which rises until the Allocation Rate is less than the Resupply Rate. From that point on, the Gap is reduced without restriction to zero.

So, the "behavior" of the simple control CLM, as revealed using STELLA, turns out to be not so simple as might be anticipated. This, of course is the value of using STELLA: It reveals the likely behavior of systems, dispelling overly simplistic expectations.
Sometimes it is straightforward to go from a symptom direct to the implicit systems that must be in some state of imbalance either within themselves or in their mutual interchanges
At other times it is less obvious,
In latter cases, a method for "thinking aloud" is useful. This method will be using the symptom "low efficiency" as an example. First, it is important to put sensible limits on depth and detail, to avoid excessive analysis.
If a symptom appears to emerge from within a single system, rather than from between two systems, the decomposition is insufficient
Identifying imbalance between pairs of implicit systems determines minimum analysis depth
Since the process of generating implicit systems via the Laundry List and the CLM is so important, a template is useful to guide and standardize the work that might be done in parallel by team members working on an Issue.
The Template shows the term POETIC at the left-hand side. This acronym is used as a guide, or aide memoire, to suggest the likely origin of possible causes. When trying to conceive possible causes of any symptom, it helps to run through the elements of POETIC to jog ideas and memories. Figure 18 amplifies the various elements of the acronym and shows how the various factors interrelate. At the center is Culture, perhaps the most intractable of all causes.
At this stage in any RSM process it is likely that a large number of implicit systems will have been generated. This may provide a rich picture of the Issue, but it is highly unlikely that such variety and profusion of implicit systems and likely causes can be sensibly addressed by normal intelligence.
The complexity problem is tackled by grouping implicit systems, and their symptomatic imbalances into groups and by identifying those groups as individual Containing Systems. This represents a hierarchy shift from detail to macro-view.
With many fewer groups (Containing Systems), it may be practicable to appreciate, understand, and propose sensible resolution of the Issue.
The figure shows the rationale behind the hierarchy shift. At the Lower Level in the figure, the implicit systems are shown shaded. They have been generated by Issue Symptoms, which are shown as arrows between their respective Implicit systems - ;since the symptoms represent an imbalance. At right and left are systems to which the Implicit Systems may be connected, but which are not directly impacted by the Issue.

At the Higher Level, the plethora of implicit systems has been aggregated into just 3 Containing Systems, by identifying groups of implicit systems that form themes. The greatly reduced number of Containing Systems still contain all the original symptoms and their probable causes, but appear in much simpler form - ;one which, perhaps, a person or team can understand and address sensibly, without being confused by complexity.
It is possible to group implicit systems using simple, obvious techniques such as the so-called "blob method" - ;see figure.
At top left, 6 implicit systems, A to F, are shown with their connections. At bottom right, they have been simply rearranged, without any change in connection logic. As a result of the rearrangement, it is evident that there are two distinct, but joined, groups, ABC and DEF. Putting a boundary around these two groups and naming them enables the complexity to be reduced from 6 interacting systems to only 2 interacting systems.
Unfortunately the blob method becomes unwieldy above 7 to 10 blobs. Moreover, the simple example shown in the figure divided conveniently into two groups. Real situations may have dozens of implicit systems, and the manner of their grouping may be neither obvious nor unique. A scientific approach is needed to deal with this situation.
As an alternative to the blob method, it is useful to employ the N2 Chart, on which Interacting systems can be presented as square matrices. Imbalances then appear in off-diagonal squares. This provides a matrix structure offering major reduction in perceived complexity

The figure shows how the example of corporate efficiency, above, looks when plotted into an N2 chart.


The figure illustrates how the N2 chart may be used to reduce Configuration Entropy, i.e. simplify the pattern of implicit systems. This is how the hierarchical shift shown above can be effected scientifically and mathematically. The figure is explained as follows,
The figure shows one of several archetypal patterns which interfaces may reveal in an N2 chart. Interfaces are shown as shaded, and the set of shaded interfaces forms a cross, centered on System D in the figure. This is the node or nexus: all systems have an interface (imbalance) with System D, and only with D. In some ideal case, System D would be the sole Issue source (c.f. the one organ to which all symptoms point)
The node always forms a cross on the N2 chart - the members of the cross form a Containing System. Where an N2 chart forms a partial cross, i.e. there are interfaces missing, it may be that the gaps identify a weakness in the analysis of symptoms, which can then be rectified.

The figure shows another common archetypal pattern formed in N2 charts.

Clustering the N2 chart, then, is not simply a matter of reducing configuration entropy. It is also an opportunity to detect and correct errors and omissions.
The figure shows one further important pattern, disjoint sets. The figure shows two blocks, but there are no connections between the blocks. This suggests that there are two independent sets of implicit systems, which may indicate that some of the original symptoms referred to a different Issue. This would not be unusual: symptoms may be gathered willy-nilly, or without particular care or understanding at the outset.
Alternatively, it may be that the symptoms all correspond to the one Issue, but that the analysis has somehow been inadequate. Summarizing,


The figure shows a practical example of a clustered N2 chart. The example is taken from a genuine business partnership. The program limits title lengths. The number '2' arises where an interface has been identified twice. As can be seen, the pattern of interfaces in the N2 chart does not form perfect archetypal patterns. There are no disjoint elements. However, partial nodes are evident, together with several incomplete functionally bound blocks. A partial node is evident at position 13, and a lesser structure is formed around B and D as a pair. On the other hand, 18, 19 and 20 evidently form a clean grouping, as only one pair of interfaces connects them to the rest.
The dotted horizontal lines delineate the Containing Systems. While the lower line is unarguable, the upper line is less so. Its placing is decided by observing the best association between the implicit systems
Wherever the lines are placed, they form Containing Systems, which are then given titles that sensibly describe the nature of the respective grouping. Interfaces that cross the horizontal lines signify connections between Containing Systems.
Having achieved the hierarchy shift, each Containing System can now be modeled in its turn, using its implicit systems as symptoms - remembering that implicit systems are those with suspect problems. From the figure, for example: -
For each Containing System, convert implicit systems into a laundry list of possible Issue Causes
Then execute the same process as for each implicit system
Having explored each Containing System, it is now possible to develop the Systems Interaction Diagram, which shows the interacting Containing Systems.
The example concerns itself with some military force providing Air Support. There have been problems of untimely weapon delivery, inaccuracies and Blue-on-Blue casualties. Three Containing Systems have been identified, complete with their shortfalls and interaction deficiencies. The whole SID presents a catalogue of problems, or (taking a more positive attitude) a list of requirements which, if met, should greatly improve the overall provision of Air Support.
The SID summarizes (likely) Issue sources. Each of the statements in the SID expresses a deficiency,
N.B. All requirement need to be met - to meet only some is to risk counterintuitive response from Issue systems. It may be the case that many of the deficiencies have to be remedied in parallel, rather than in sequence according to some arbitrary priority scheme. At other times, it may be evident that there are key deficiencies which, if remedied, will result in a domino resolution of other deficiencies.
Where such doubts exist, it is useful to develop a dynamic simulation from the SID. This is done using the Containing Systems' CLMs as a precursor to the dynamic simulation. Once the simulation is in place, different remedies can also be simulated, applied and compared. That which best meets satisfies the original symptoms is the preferred remedy.
The locus of possible causes encompassed all possible sources of Issue, including some which were probably not at fault. The hierarchy shift focuses on Containing Systems, and their interaction: this is a perspective shift from (e.g.) tactical to strategic, from micro to macro. Requirements, which are generated at macro-level, should address underlying weaknesses and shortcomings. They are unlikely to concentrate on specific and incorrect cause, but they could overlook some genuine, detailed cause.
Verification against initial symptoms therefore ensures requirements are-
a. necessary
b. sufficient
Interestingly, this also means that RSM is forgiving of minor errors, particularly in the early stages
We have introduced the Rigorous Soft method RSM is a powerful, heavyweight tool, to unravel substantial issues. As with any advanced tool, it takes practice to become familiar with RSM. The method works well with heterogeneous teams, whose members bringing a broad background to the table. Team members take time to bond, so first results may fall short of expectations.
In fact, of course, RSM is a context-free method, so that the outputs from it are governed to a major extent by the data fed in by team members. Choosing the right team to use RSM may be a key issue in its own right.
Updated 2007