Structure of a System

“If we use Integrated PM Systems for our projects, then we can get better project Performance, but it helps to learn a little about systems thinking.”

We choose to define a system as follows:

1. A system is an organized assembly of components. 'Organized' means that there exist special relationships between the components. In the Integrated PM System, components include tasks, issues, requirements, market evidence, problem statements, goals, and risks. The ‘organized’ condition would include WBS features such as parent-child relationships, predecessors, and other policies and procedures.

2. The system does something, i.e. it exhibits behaviors that are unique to the system. The accomplishment of a goal can be the ‘something’, but systems may not accomplish the goal and still be a system. The behavior indicated here is a sequence of state variable changes. Every project has a unique sequence of state variable changes, and is that system’s behavior up to that point of time.

3. Each component contributes towards the behavior of the system and its own behavior is affected by being in the system. No component has an independent effect on the system. A part that has an independent effect and is not affected by the system is an input. (See #5 below.) The behavior of the system is changed if any component is removed or leaves.

4. Groups of components within the system may by themselves have properties (1), (2), and (3), i.e. they may form subsystems. Without 1,2, and 3 then they are just components, not subsystems.

5. The system has an outside - an environment - which provides inputs into the system and receives outputs from the system.

6. The system has been identified by someone to be of special interest for a given purpose or goal.

The relationships between components may be unidirectional and/or causal, i.e. Task A affects Task B, but is not in turn affected by B. They may be mutual, i.e. Task A and B both affect each other. Mutual influences or causality increase the complexity of system behavior.

The crucial ingredients of a system are therefore its components, the relation-ships between the components, the behavior or the activities of the system, its relevant environment, the inputs from the environment, the outputs to the environment, and the special interest of the observer.

A system is not a mere collection of parts that do not interact with each other. i.e. it is not a chaotic aggregate, such as a pile of rocks. Adding a few parts to a chaotic aggregate or removing some does not change its nature. Doing so in a system will affect its behavior. Similarly, a chaotic aggregate does not do anything, while a system does or at least is capable of doing things under specific conditions.

System components do not have to be physical things. They can be abstract things, such as information, risks, resources, numerical variables that measure things, like cumulative costs or levels of achievement, and relationships between physical or abstract things. In fact, most systems of interest in decision making may often consist of abstract things and their relationships alone.

An example of two overlapping systems is the execution of two projects, sharing the same resources, budget constraints, and information assets. This overlapping may produce a ‘higher’ system, where the one system contains both subsystems, such as in a program.

What a system does- its activity- is of prime interest to the observer, a decision maker or an analyst. The system behavior consists of a transformation process, i.e. inputs from the environment are transformed into outputs.

Examples of such transformation processes are living plants, which when exposed to light transform water and carbon dioxide (inputs) into carbohydrates and oxygen (outputs), or a manufacturing firm, which transforms raw materials (inputs) into finished products for sale to customers (outputs), or resources, such as funds, labor and expertise of people (inputs), into profit (outputs). Product systems transform information assets such as product features into market requirements and product launches.

The relevant environment of a system consists of all those aspects that affect system behavior in any form, and those aspects that are affected by it, but do not in turn affect it. Actors and decision makers are part of the system environment because they do impact the system, but they are not impacted by the system and are free to act independently from the system. Some folks argue that the system does impact the decision maker, if only to change their mood. But this is inaccurate, the decision maker can choose not to respond. They are viewed as being outside the system. The decision maker can provide inputs to the system or receive outputs from the system.

Inputs are things the system needs to function but does not produce for itself, or if so, only in insufficient quantities, such as resources or information. Inputs may also be in the form of constraints on the behavior of the system, e.g. by setting quality standards or equipment capacities.

Many of the system inputs are uncontrollable or assumed to be so. They are given and cannot be affected by the decision maker, such as directives of the Program Office. However, aspects over which the decision maker has control are controllable inputs. The control may be in the form of being able to select the value of a decision variable, choosing one of a range of actions to take, a decision about the amount of certain resources, such as funds, to be made available to the system, or a set of decision rules to follow whenever the behavior of the system exhibits certain conditions, or a specified event occurs.

Outputs are things the system 'releases' or gives to the environment, such as goods and services, information, funds, and waste products. They also include measures of performance or other indicators of system behavior. The purpose for studying a system, determines which ones an observer may want to measure.

The relevant environment is in turn embedded in an even larger environment - 'the universe' - which is assumed not to affect the system; nor is it affected by the system, i.e. it is irrelevant and can be ignored.

Finally, the person studying a system has a purpose for doing so. This could be to gain a better understanding of system behavior, e.g. for a natural system. For human activity systems, the 'observer' is usually the decision maker, interested in how to control system behavior, e.g. how to achieve maximum output.


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