Articulating Reality

Causal loop diagrams provide a language for articulating our understanding of the dynamic, interconnected nature of our world. We can think of them as sentences which are constructed by linking together key variables and indicating the causal relationships between them. By stringing together several loops, we can create a coherent story about a particular problem or issue.

The next page includes some suggestions on the mechanics of creating causal loop diagrams. Below are some more general guidelines that should help lead you through the process:

• Theme Selection. Creating causal loop diagrams is not an end unto itself, but part of a process of articulating and communicating deeper insights about complex issues. It is pointless to begin creating a causal loop diagram without having selected a theme or issue that you wish to understand better. “To understand the implications of changing from a technology-driven to a marketing-oriented strategy,” for example, is a better theme than “To better understand our strategic planning process.”
• Time Horizon. It is also helpful to determine an appropriate time horizon for the issue — one long enough to see the dynamics play out. For a change in corporate strategy the time horizon may span several years, while a change in advertising campaigns may be on the order of months.

Time itself should not be included as a causal agent, however. After a heavy rainfall a river level steadily rises overtime, but we would not attribute it to the passage of time. You need to identify what is actual driving the change. In computer chips, $/MIPS million instructions per second) have been decreasing in a straight line over the past decade. It would be incorrect, however, to draw a causal connection between time and $/MIPS. Instead, increasing investments and learning curve effects are likely causal forces.

• Behavior Over Time Charts. Identifying and drawing out the behavior over time of key variables is an important first step toward articulating the current understanding of the system. Drawing out future behavior means taking a risk — the risk of being wrong. The fact is, any projection of the future will be wrong, but by making it explicit, we can test our assumptions and uncover inconsistencies that may otherwise never get surfaced. For example, drawing projections of steady productivity growth while training dollars are shrinking raises the question “If training is not driving our growth, what will?” The behavior over time diagram also points out key variables that should be included in the diagram, such as Training Budget and Productivity. Your diagram should try to capture the structure that will produce the projected behavior.
• Boundary Issue. How do you know when to stop adding to your diagram? If you don’t stay focused on the issue, you may quickly find yourself overwhelmed by the number of connections possible. Remember, you are not trying to draw out the whole system – only what is critical to the theme being addressed. When in doubt about including something, ask “If I were to double or halve this variable, would it have a significant effect on the issue I am mapping?” If not, it probably can be omitted.
• Level of Aggregation. How detailed should the diagram be? Again, the level should be determined by the issue itself. The time horizon also can help determine how detailed the variables need to be. If the time horizon is on the order of weeks (fluctuations on the production line), variables that change slowly over a period of many years may be assumed to be constant(such as building new factories). As a rule of thumb, the variables should not describe specific events (a broken pump); they should represent patterns of behavior (pump breakdowns throughout the plant).
• Significant Delays. Make sure to identify which (if any) links have significant delays relative to the rest of the diagram. Delays are important because they are often the source of imbalances that accumulate in the system. It may help to visualize pressures building up in the system by viewing the delay connection as a relief valve that either opens slowly as pressure builds or opens abruptly when the pressure hits a critical value. An example of this might be a delay between long work hours and burnout: after sustained periods of working 60+ hours per week, a sudden collapse might occur in the form of burnout.
  

  TOOL BOX: GUIDELINES FOR DRAWING CAUSAL LOOP DIAGRAMS

  

The post Guidelines for Drawing Causal Loop Diagrams appeared first on The Systems Thinker.

For example, in August, White House Science Adviser John Marburger briefed a Senate panel on climate change, saying, “We know we have to make very large changes if this turns out to be a problem. The consequences of human-induced global warming could be quite severe.” Yet at the same briefing, the administration stood behind its “wait and see” policy, articulated by President Bush in February: we should only “slow the growth of greenhouse gas emissions,

and—as the science justifies—stop, and then reverse that growth.” Climate change could be severe, and yet we should wait before acting. How can U. S. leadership reconcile these two seemingly contradictory statements?

Climate As a Delayed System

MIT professor John Sterman and Harvard’s Linda Booth Sweeney explain that this “wait and see” approach makes sense if you believe the world’s climate to be a nondelayed, responsive system in which a change in human activity has an immediate effect. Their recent experiments confirm that many highly competent people instinctively see climate as behaving this way. Most of their business-school student subjects thought that if humans reduced emissions of GHGs, the storehouse of those gases in the atmosphere would promptly decline and global temperature would follow.

CO2 IN THE ATMOSPHERE

Carbon dioxide (CO2) in the atmosphere, the primary heat-trapping gas, can be thought of as a stock or accumulation. The stock is now at its highest level in almost half a million years. To reduce the ecological and economic changes from producing global warming, we need to lower the level of the stock by reducing the inflow (CO2 emission rate) to less than the outflow (Net CO2 removal rate).

The inflow is currently about double the outflow. If we were to reduce the inflow by, say, 20 percent, it would still be greater than the outflow and the level of CO2 would continue to rise, albeit at a slower rate. No wonder the students predicted incorrectly—it is counterintuitive to think that the CO2 emission rate can go down while the level of CO2 in the atmosphere continues to go up! Nevertheless, it’s true. If the removal rate were constant, we would need to cut the inflow rate by more than 50 percent to finally begin to lower the CO2 level. The bottom line is this: If we, as the Bush administration says, “slow the growth of greenhouse gas emissions, and—as the science justifies—stop, and then reverse that growth,” it could still take many decades for levels of CO2 in the atmosphere to decline.

A Robust Plan

If we believe Mr. Marburger that the effects of climate change could be “quite severe,” we need a robust plan.

The Bush administration’s plan would work well if the climate had short delays. But the plan is not robust when managing a slow-responding system like our climate; the possibility of negative, irreversible effects from waiting are too high.

We see two important steps. 1. Teach ourselves the basic mechanics of our climate.

Prudence leads us to act now to educate ourselves about the dynamics of the climate system and to address the source of the problem with practical measures. If Sterman and Booth Sweeney are right, our generally poor intuition about the climate enables many of us to accept a “wait and see” approach. For our society to engage in an effective public discourse about global warming, we need to ground ourselves in the basics of the climate inflows, levels, and outflows. Then we can evaluate the impact of national-level proposals and really understand the challenge that we face in stabilizing the climate.

2. Act now to reduce GHG emissions. The best way to deal with a slow-moving system in which we know we will eventually need to make a change is to begin the change as early as possible. We need not initially focus on retooling our entire industrial base; we can begin with the significant reduction in emissions available through hybrid cars, better designed industrial motors, fuel cells, and renewable energy production. Such improvements could come at relatively low cost, improve our short-term economic vitality, and reduce energy dependence.

How can we get the process started? We suggest designing incentives and rewards that would unleash people’s tremendous capacity for innovation. A similar outpouring of new ideas came as a result of the ban on CFCs to prevent additional damage to the ozone layer. Let’s introduce similar mechanisms into our market system to encourage technological and behavioral changes for reducing GHG emissions.

Prudence leads us to act now to educate ourselves about the dynamics of the climate system and to address the source of the problem with practical measures. These actions will not be easy—technologically, culturally, or politically. But they are certainly easier than navigating a barge while pretending it will handle like a Ferrari.

The post We Can’t Afford to “Wait and See” on Climate Changes appeared first on The Systems Thinker.

Causal loop diagrams provide a language for articulating our understanding of the dynamic, interconnected nature of our world.

Articulating Reality

Causal loop diagrams provide a language for articulating our understanding of the dynamic, interconnected nature of our world. We can think of them as sentences that are constructed by linking together key variables and indicating the causal relationships between them. By stringing together several loops, we can create a coherent story about a particular problem or issue.

Following are some more general guidelines that should help lead you through the process:

• Theme selection. Creating causal loop diagrams is not an end unto itself, but part of a process of articulating and communicating deeper insights about complex issues. It is pointless to begin creating a causal loop diagram without having selected a theme or issue that you wish to understand better. “To understand the implications of changing from a technology-driven to a marketing-oriented strategy,” for example, is a better theme than “To better understand our strategic planning process.”
• Time horizon. It is also helpful to determine an appropriate time horizon for the issue—one long enough to see the dynamics play out. For a change in corporate strategy, the time horizon may span several years, while a change in advertising campaigns may be on the order of months.

  Time itself should not be included as a causal agent, however. After a heavy rainfall, a river level steadily rises over time, but we would not attribute it to the passage of time. You need to identify what is actually driving the change. In computer chips, $/MIPS (million instructions per second) decreased in a straight line in the 1990s. It would be incorrect, however, to draw a causal connection between time and $/MIPS. Instead, increasing investments and learning curve effects were likely causal forces.

• Behavior over time charts. Identifying and drawing out the behavior over time of key variables is an important first step toward articulating the current understanding of the system. Drawing out future behavior means taking a risk—the risk of being wrong. The fact is, any projection of the future will be wrong, but by making it explicit, we can test our assumptions and uncover inconsistencies that may otherwise never get surfaced. For example, drawing projections of steady productivity growth while training dollars are shrinking raises the question, “If training is not driving our growth, what will?” The behavior over time diagram also points out key variables that should be included, such as Training Budget and Productivity. Your diagram should try to capture the structure that will produce the projected behavior.
• Boundary issue. How do you know when to stop adding to your diagram? If you don’t stay focused on the issue, you may quickly find yourself overwhelmed by the number of connections possible. Remember, you are not trying to draw out the whole system—only what is critical to the theme being addressed. When in doubt, ask, “If I were to double or halve this variable, would it have a significant effect on the issue I am mapping?” If not, it probably can be omitted.
• Level of aggregation. How detailed should the diagram be? Again, the level should be determined by the issue itself. The time horizon also can help determine how detailed the variables need to be. If the time horizon is on the order of weeks (fluctuations on the production line), variables that change slowly over a period of many years may be assumed to be constant (such as building new factories). As a rule of thumb, the variables should not describe specific events (a broken pump); they should represent patterns of behavior (pump breakdowns throughout the plant).
• Significant delays. Make sure to identify which (if any) links have significant delays relative to the rest of the diagram. Delays are important because they are often the source of imbalances that accumulate in the system. It may help to visualize pressures building up in the system by viewing the delay connection as a relief valve that either opens slowly as pressure builds or opens abruptly when the pressure hits a critical value. An example of this might be a delay between long work hours and burnout: After sustained periods of working 60+ hours per week, a sudden collapse might occur in the form of burnout.

See detailed guidelines for drawing causal loop diagrams.

The post Guidelines for Drawing Causal Loop Diagrams appeared first on The Systems Thinker.

Weighing the Risk

In recent years, groups that oppose vaccinations because of their potential health risks have sprung up. For instance, some activists claim that the mumps, measles, rubella vaccine is linked to autism, although medical groups studying the possible connection have concluded that the vaccine is not to blame. Anti-immunization groups also doubt the government’s ability to oversee vaccine safety, pointing to, among other things, its delay in banning mercury from injections, despite the fact that it can impair children’s cognitive development.

In response to such concerns, more and more people are choosing not to vaccinate. When weighing the risk of contracting vaccine-preventable diseases against that of experiencing one of the rare catastrophic reactions to the vaccine itself, they are banking on current low levels of infection and deciding to avoid the injections.

Health officials acknowledge that vaccines can cause side effects, ranging from mild (temporary pain at the injection site) to serious (between 1960 to 1999, 8 to 10 children a year in the U. S. contracted paralytic polio from the oral polio vaccine).

But they also point out that as more people avoid immunization, the incidence of certain serious diseases is bound to rise. As just one example, the Consumer Reports article cites the case of Mary Catherine Walther, who contracted Hib meningitis on her first birthday. Her local hospital in Tennessee hadn’t treated a case of the illness for eight years, since the introduction of a vaccine against it. Fortunately, the toddler recovered.

THE SWING OF RELATIVE RISK

As the incidence of a disease rises, people’s perception of the risk to their own health increases. Under these conditions, they are more likely to overlook the vaccine’s side effects. Use of the vaccine reduces the incidence of the disease. When infection rates fall, people’s concerns about vaccine safety grow. If enough people choose not to use the vaccine, the disease begins to spread again.

One reason that formerly dormant diseases can reappear is that they haven’t yet been eradicated worldwide. Travelers from countries where immunization programs have been limited can carry a disease to other regions. Or such illnesses could reemerge through more diabolical means. In June, a simulation exercise depicted a smallpox attack by terrorists that infected 24 people in Oklahoma. After an imaginary two weeks, 16,000 people in 25 states were infected; 1,000 were dead; and 10 other countries reported cases. Following these trends, within three weeks, there would be 300,000 victims, a third of whom would die. Without continued vigilance, such an epidemic could also happen with other serious illnesses that we have long thought were cured.

Relative Risk

The pendulum swing between concerns about disease to concerns about the vaccines themselves represents a classic balancing process (see “The Swing of Relative Risk”). When the threat of a specific disease is high, the vaccine’s desirability rises, regardless of safety concerns. When incidences of the disease are few and far between, people start raising questions about the vaccine’s side effects.

Rather than writing off such concerns as irrational, by recognizing this dynamic, public-health officials can anticipate and manage them through ongoing investments in vaccine safety, education, and immunization programs around the world. In fact, officials might consider activists’ skepticism to be a positive force, in that it keeps pressure on manufacturers and governmental agencies to continually improve these life-saving products. After all, no one wants the cure to be worse than the sickness.

Janice Molloy is managing editor of The Systems Thinker.

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