leverage points
Posted: Wed Jul 09, 1997 9:51 pm
At SDSG, LLC (The Strategic Decision Simulation Group), we have been
refining methods for identifying leverage points in systemic models for
several years. James Ritchie-Dunham of SDSG will be presenting a paper on
our methodologies at the International SD conference in Istanbul in August.
In Donella Meadows original query regarding leverage points, she proposes a
hierarchy of increasingly effective places to intervene in a system. We
would note that Donella proposes a hierarchy of increasing effectiveness
which begins with SD inputs and proceeds "upward" through such parameters as
delays, "strength", gain, and structure, culminating in the psychological
models of the people as the most effective points for intervention.
Traditionally, SD practitioners have focused predominantly upon the
characteristics of the system. While Donellas list is appealing as a
general interpretation of system behavior, we have developed specific tools
that help practitioners identify useful leverage points. From a purely SD
perspective we would propose that the "effectiveness of a leverage point"
should be essentially the derivative of system behavior with respect to the
change in the element under consideration. More effective leverage points
would have more impact. This requires an operating model for evaluation.
For our work, we prefer to think of leverage points as those points in the
model with high "influence" based upon the structure of the model. (By
focusing on the structure we can seek leverage points in preliminary causal
and stock-flow models and can begin giving the client useful, thought
provoking output much sooner than is required for a calibrated/validated
model.) In our work leverage points have relatively high statistical impact
on other variables in the system, implying (but certainly not guaranteeing)
a large impact on the behavior of the system. Once high-influence
(leverage) points are identified, we further classify them as either having
high exposure to other variables (relatively difficult to control) or
limited exposure (relatively easy to control). It is our experience that
highly exposed "levers" are very difficult to change in complex systems --
the system itself often resists the change -- such that even if the variable
would be an effective lever IF one could change the it, substantial and
coordinated effort are required to acheive the change. As a result, a
portion our work focuses on differentiating "leverage points" which are
within local control (of departments or divisions) and those requiring
broader control (across departments or divisions). Our tool kit automates
the (mathematical) determination of exposure and influence from causal and
stock/flow diagrams and effectively determines a variables leverage in the
system.
A second important distinction we would suggest is that the structural and
systemically-determined leverage points are secondary to the clients
mental model. As consultants working with senior management on real world
problems, there "is no leverage" unless the clients mental models
accommodate the lever. This focuses our initial efforts on capturing the
clients mental models and paradigms, and then on helping them understand
the leverage points within their understanding of the world. Please note:
this does not mean we do not challenge our clients to arrive at an
enlightened model -- we do. However, it is imperative that the client "own"
and understand the model if they are to use it to adjust their world. Once
we arrive at an agreed model, then we can begin to help them consider and
understand the structural implications of their paradigms and thought
processes. Client participation in the process is mandatory. Only by
changing or developing the clients mental models can the systems consultant
impact on the client behavior. We would suggest that the logical sequence
when working with clients is to begin at the top (number 1) of Donellas
list and to work down to the model details. As far as the specific items on
Donellas list are concerned, we find the specific sequence relatively
unimportant as the value of any specific intervention site will, in our
experience, shift with model structure and client paradigms.
I look forward to your comments!
Jay Forrest
The Strategic Decision Simulation Group (SDSG, L.L.C.)
jayf@sdsg.com
http://www.sdsg.com
(281)493-5022 (voice) (281)558-3228 (fax)
refining methods for identifying leverage points in systemic models for
several years. James Ritchie-Dunham of SDSG will be presenting a paper on
our methodologies at the International SD conference in Istanbul in August.
In Donella Meadows original query regarding leverage points, she proposes a
hierarchy of increasingly effective places to intervene in a system. We
would note that Donella proposes a hierarchy of increasing effectiveness
which begins with SD inputs and proceeds "upward" through such parameters as
delays, "strength", gain, and structure, culminating in the psychological
models of the people as the most effective points for intervention.
Traditionally, SD practitioners have focused predominantly upon the
characteristics of the system. While Donellas list is appealing as a
general interpretation of system behavior, we have developed specific tools
that help practitioners identify useful leverage points. From a purely SD
perspective we would propose that the "effectiveness of a leverage point"
should be essentially the derivative of system behavior with respect to the
change in the element under consideration. More effective leverage points
would have more impact. This requires an operating model for evaluation.
For our work, we prefer to think of leverage points as those points in the
model with high "influence" based upon the structure of the model. (By
focusing on the structure we can seek leverage points in preliminary causal
and stock-flow models and can begin giving the client useful, thought
provoking output much sooner than is required for a calibrated/validated
model.) In our work leverage points have relatively high statistical impact
on other variables in the system, implying (but certainly not guaranteeing)
a large impact on the behavior of the system. Once high-influence
(leverage) points are identified, we further classify them as either having
high exposure to other variables (relatively difficult to control) or
limited exposure (relatively easy to control). It is our experience that
highly exposed "levers" are very difficult to change in complex systems --
the system itself often resists the change -- such that even if the variable
would be an effective lever IF one could change the it, substantial and
coordinated effort are required to acheive the change. As a result, a
portion our work focuses on differentiating "leverage points" which are
within local control (of departments or divisions) and those requiring
broader control (across departments or divisions). Our tool kit automates
the (mathematical) determination of exposure and influence from causal and
stock/flow diagrams and effectively determines a variables leverage in the
system.
A second important distinction we would suggest is that the structural and
systemically-determined leverage points are secondary to the clients
mental model. As consultants working with senior management on real world
problems, there "is no leverage" unless the clients mental models
accommodate the lever. This focuses our initial efforts on capturing the
clients mental models and paradigms, and then on helping them understand
the leverage points within their understanding of the world. Please note:
this does not mean we do not challenge our clients to arrive at an
enlightened model -- we do. However, it is imperative that the client "own"
and understand the model if they are to use it to adjust their world. Once
we arrive at an agreed model, then we can begin to help them consider and
understand the structural implications of their paradigms and thought
processes. Client participation in the process is mandatory. Only by
changing or developing the clients mental models can the systems consultant
impact on the client behavior. We would suggest that the logical sequence
when working with clients is to begin at the top (number 1) of Donellas
list and to work down to the model details. As far as the specific items on
Donellas list are concerned, we find the specific sequence relatively
unimportant as the value of any specific intervention site will, in our
experience, shift with model structure and client paradigms.
I look forward to your comments!
Jay Forrest
The Strategic Decision Simulation Group (SDSG, L.L.C.)
jayf@sdsg.com
http://www.sdsg.com
(281)493-5022 (voice) (281)558-3228 (fax)