| GLOSSARY
OF TERMS
Systems
thinking can serve as a language for communicating about complexity
and interdependencies. To be fully conversant in any language, you
must gain some mastery of the vocabulary, especially the phrases
and idioms unique to that language. This glossary lists many terms
that may come in handy when you're faced with a systems problem.
Accumulator
Anything that builds up or dwindles; for example, water in a bathtub,
savings in a bank account, inventory in a warehouse. In modeling
software, a stock is often used as a generic symbol for accumulators.
Also known as Stock or Level.
Balancing Process/Loop
Combined with reinforcing loops, balancing processes form the building
blocks of dynamic systems. Balancing processes seek equilibrium:
They try to bring things to a desired state and keep them there.
They also limit and constrain change generated by reinforcing processes.
A balancing loop in a causal loop diagram depicts a balancing process.
Balancing Process with Delay
A commonly occurring structure. When a balancing process has
a long delay, the usual response is to overcorrect. Overcorrection
leads to wild swings in behavior. Example: real estate cycles.
Behavior Over Time (BOT) Graph
One of the 10 tools of systems thinking. BOT graphs capture the
history or trend of one or more variables over time. By sketching
several variables on one graph, you can gain an explicit understanding
of how they interact over time. Also called Reference Mode.
Causal Loop Diagram (CLD) One of the 10 tools of systems
thinking. Causal loop diagrams capture how variables in a system
are interrelated. A CLD takes the form of a closed loop that depicts
cause-and-effect linkages.
Drifting Goals
A systems archetype. In a "Drifting Goals" scenario, a
gradual downward slide in performance goals goes unnoticed, threatening
the long-term future of the system or organization. Example: lengthening
delivery delays.
Escalation
A systems archetype. In the "Escalation" archetype, two
parties compete for superiority in an arena. As one party's actions
put it ahead, the other party "retaliates" by increasing
its actions. The result is a continual ratcheting up of activity
on both sides. Examples: price battles, the Cold War.
Feedback
The return of information about the status of a process. Example:
annual performance reviews return information to an employee about
the quality of his or her work.
Fixes That Fail
A systems archetype. In a "Fixes That Fail" situation,
a fix is applied to a problem and has immediate positive results.
However, the fix also has unforeseen long-term consequences that
eventually worsen the problem. Also known as "Fixes That Backfire."
Flow
The amount of change something undergoes during a particular unit
of time. Example: the amount of water that flows out of a bathtub
each minute, or the amount of interest earned in a savings account
each month. Also called a Rate.
Generic Structures
Structures that can be generalized across many different settings
because the underlying relationships are fundamentally the same.
Systems archetypes are a class of generic structures.
Graphical Function Diagram (GFD)
One of the 10 tools of systems thinking. GFDs show how one variable,
such as delivery delays, interacts with another, such as sales,
by plotting the relationship between the two over the entire range
of relevant values. The resulting diagram is a concise hypothesis
of how the two variables interrelate. Also called Table Function.
Growth and Underinvestment
A systems archetype. In this situation, resource investments in
a growing area are not made, owing to short-term pressures. As growth
begins to stall because of lack of resources, there is less incentive
for adding capacity, and growth slows even further.
Learning Laboratory
One of the 10 tools of systems thinking. A learning laboratory embeds
a management flight simulator in a learning environment. Groups
of managers use a combination of systems thinking tools to explore
the dynamics of a particular system and inquire into their own understanding
of that system. Learning labs serve as a manager's practice field.
Level
See Accumulator.
Leverage Point
An area where small change can yield large improvements in a system.
Limits to Success
A systems archetype. In a "Limits to Success" scenario,
a company or product line grows rapidly at first, but eventually
begins to slow or even decline. The reason is that the system has
hit some limit—capacity constraints, resource limits, market
saturation, etc.—that
is inhibiting further growth. Also called "Limits to Growth."
Management Flight Simulator (MFS)
One of the 10 tools of systems thinking. Similar to a pilot's flight
simulator, an MFS allows managers to test the outcome of different
policies and decisions without "crashing and burning"
real companies. An MFS is based on a system dynamics computer model
that has been changed into an interactive decision-making simulator
through the use of a user interface.
Policy Structure Diagram
One of the 10 tools of systems thinking. Policy structure diagrams
are used to create a conceptual "map" of the decision-making
process that is embedded in an organization. It highlights the factors
that are weighed at each decision point.
Rate
See Flow.
Reference Mode
See Behavior Over Time Graph.
Reinforcing Process/Loop
Along with balancing loops, reinforcing loops form the building
blocks of dynamic systems. Reinforcing processes compound change
in one direction with even more change in that same direction. As
such, they generate both growth and collapse. A reinforcing loop
in a causal loop diagram depicts a reinforcing process. Also known
as vicious cycles or virtuous cycles.
Shifting the Burden
A systems archetype. In a "Shifting the Burden" situation,
a short-term solution is tried that successfully solves an ongoing
problem. As the solution is used over and over again, it takes attention
away from more fundamental, enduring solutions. Over time, the ability
to apply a fundamental solution may decrease, resulting in more
and more reliance on the symptomatic solution. Examples: drug and
alcohol dependency.
Shifting the Burden to the Intervener
A special case of the "Shifting the Burden" systems
archetype that occurs when an intervener is brought in to help solve
an ongoing problem. Over time, as the intervener successfully handles
the problem, the people within the system become less capable of
solving the problem themselves. They become even more dependent
on the intervener. Example: ongoing use of outside consultants.
Simulation Model
One of the 10 tools of systems thinking. A computer model that lets
you map the relationships that are important to a problem or an
issue and then simulate the interaction of those variables over
time.
Stock
See Accumulator.
Structural Diagram
Draws out the accumulators and flows in a system, giving an
overview of the major structural elements that produce the system's
behavior. Also called flow diagram or accumulator/flow diagram.
Structure-Behavior Pair
One of the 10 tools of systems thinking. A structure-behavior pair
consists of a structural representation of a business issue, using
accumulators and flows, and the corresponding behavior over time
(BOT) graph for the issue being studied.
Structure
The manner in which a system's elements are organized or interrelated.
The structure of an organization, for example, could include not
only the organizational chart but also incentive systems, information
flows, and interpersonal interactions.
Success to the Successful
A systems archetype. In a "Success to the Successful"
situation, two activities compete for a common but limited resource.
The activity that is initially more successful is consistently given
more resources, allowing it to succeed even more. At the same time,
the activity that is initially less successful becomes starved for
resources and eventually dies out. Example: the QWERTY layout of
typewriter keyboards.
System Dynamics
A field of study that includes a methodology for constructing computer
simulation models to achieve better understanding of social and
corporate systems. It draws on organizational studies, behavioral
decision theory, and engineering to provide a theoretical and empirical
base for structuring the relationships in complex systems.
System
A group of interacting, interrelated, or interdependent elements
forming a complex whole. Almost always defined with respect to a
specific purpose within a larger system. Example: An R&D department
is a system that has a purpose in the context of the larger organization.
Systems Archetypes
One of the 10 tools of systems thinking. Systems archetypes are
the "classic stories" in systems thinking—common
patterns and structures that occur repeatedly in different settings.
Systems Thinking
A school of thought that focuses on recognizing the interconnections
between the parts of a system and synthesizing them into a unified
view of the whole.
Table Function
See Graphical Function Diagram.
Template
A tool used to identify systems archetypes. To use a template, you
fill in the blank variables in causal loop diagrams.
Tragedy of the Commons
A systems archetype. In a "Tragedy of the Commons"
scenario, a shared resource becomes overburdened as each person
in the system uses more and more of the resource for individual
gain. Eventually, the resource dwindles or is wiped out, resulting
in lower gains for everyone involved. Example: the Greenhouse Effect.
The
above glossary is a compilation of definitions from many sources,
including:
• Innovation Associates' and GKA's Introduction to Systems
Thinking coursebooks
• The Fifth Discipline: The Art and Practice of the Learning
Organization, by Peter Senge
• High Performance Systems' Academic User's Guide to STELLA
• The American Heritage Dictionary and The Random House Dictionary.
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