| Worksheet W08 - System Analysis 3 - System's feedback diagram|
|Table of Contents|
|2. Putting into Practice|
|4. Software, templates and other support|
|5. Call on Resources|
|6. Literature, examples and background information|
The System’s Feedback Diagram is used to analyze the indirect causal loops that determine a system's behaviour and show its actual interrelations. It allows various interpretations, gives a good overview of the system and enables easy the communication within the project team. It is part of a three-tier toolkit with the Cross Impact Analysis and the Feedback Diagram.
2.1 When and why should this tool be used?
This tool will show the effects of changing a variable in a system, for instance by creating a new PSS offer. The tool enables to focus on the overall behaviour of the new system, its cycle indirect interactions and time delays. The goal is to optimise the system both in terms of sustainable development orientation and to find out how the new PSS fits in this system and what it changes.
2.2 Who should use this tool?
The network of the feedback diagram has to be built up in the working group, where in a common discussion process it will be worked out step by step.
3.1 How should this tool be used?
The diagram adds information to the list of variables by arranging them according to their network of mutual influence. It shows direction and quality of the relations. However it still contains no information about quantitative aspects like the intensity of the existing relations and interactions (these would be done in a dynamic simulation. It is not part of MEPSS).
To work out a Feedback Diagram one lists all similarly directed and all contrary directed relations of all variables independent from the cross impact analysis.
The relations will be pictured by using the roles in figure 1.
The result is a plenty of overlapping positive and negative feedback loops. These feedback loops and the different role of the variables in it will be the basis for the cybernetic interpretation.
The result is the diagram itself. It’s cybernetic interpretation that helps to understand the system behaviour and to find successful ways of changing options by new PSS. It may be the basic of a dynamic evaluation process.
3.3 Input needed/ data required/ data acquisition process
The feedback diagram will be worked out by the working group. They use the set of defined variables, the material and the dates of the first steps of system analysis.
The “Studiengruppe für Biologie und Umwelt GmbH” has created a software named “Sensitivitätsmodell Prof. Vester“. It is available at www.frederic-vester.de.
4.2 Templates and other support
5.1 Personnel and time needed
A working group of 3 to 5 experts will be able to work out a complete system analysis in 1 to 3 months depending on their experience and the size of the system.
6.1 Methodological References
Literature and references will find on www.frederic-vester.de.