• Pressure: activity causing state
   
  
• State: condition that exists
   
  
• Response: actions to change state

• State is the condition that exists
   
  
• Response is what is being done to try to fix the state
   
  
• Pressure is what is causing the state
   
  
• Pressure is most important but frequently neglected
   
  
• Pressure-state-response is like ripples on a pond

Traditionally, organizations tend to measure conditions that exist. This is called the state. For example, an environmental agency measures the condition of the air--the air quality--by measuring how many parts per million of a pollutant are in the air or how many days the air quality is rated "good." These are measures of the state of air quality.

An agency may also measure responses related to that state: how many air permits were issued or what emissions standards have been set for automobiles? These are measures of response to the state of air quality.

However, frequently what is not measured is the activity that is causing the state to exist. This activity is called the pressure. In the case of air quality, examples of pressure are the number of cars being driven and the amount that they are driven. When you develop indicators, make sure you pay attention and measure pressures in addition to states and responses.

(Note: The pressure-state-response framework was developed for environmental issues and works well for those types of indicators. It is harder to apply this framework to social and economic issues. It helps to establish a context and draw a boundary around a problem before deciding what the pressures, states, and responses are.

For example, if the issue is crime, as defined by "the number of robberies," then the context is "safety." The number of crimes is the "state." A response might be to hire more police officers. The number of police officers is a measure of the "response." There are a number of "pressures" that may be causing the "state" to exist, including drug use and poverty. The amount of drug use or the lack of jobs are measures of the "pressures." These pressures and responses define the boundary of the issue.

However, it is possible to see the lack of jobs as a "state" if the context is "economic well-being." In this case, welfare and job training are both "responses" to the state; as a society, two responses that we have to the lack of jobs are: giving people money (welfare) and helping people develop skills (job training).

Both of these responses need to be measured, but there should also be a measure of the pressures causing the lack of jobs. Examples of pressures causing lack of jobs include increased mechanization and the shifting of jobs to places with lower wage rates.

In a sense, the shifting of jobs to places with lower wage rates can be seen as a pressure causing crime (a state) and job training (a response to crime), but they are both outside the boundary of the original context of "safety." Setting the boundary of the context helps to keep the discussion focused.

Another difficulty with pressure-state-response discussions is that some things may be a pressure in one context and a state or response in another. For example, if the context is air quality, then the amount of air pollution is the state and a pressure would be the number of cars being driven. However, if the context is transportation, the state becomes the number of cars driven and a pressure may by the distance between where people live and where they work. Again, it is important to understand the context and the boundaries.

Discussions of pressure-state-response can be like the ripples caused by throwing a stone into a pond-everything leads to something else. Understanding the ripples of the cause and effect relationships is an important part of developing better indicators.)