logical processes that are especially sensitive to stresses and perturbations. Future research may suggest better indicators, but their performance and reliability need to be carefully evaluated before implementing them nationally.

The committee suggests that the development of indicators used as “common currency” should be an open democratic process involving agencies, industry, and other stakeholders. Only if there is agreement of what to monitor will the results be accepted.

Recommendation 6.6: There should be an open and deliberative process involving stakeholders to establish criteria for environmental monitoring programs.

The committee follows the arguments for a common currency developed by the indicators committee (NRC 2000a):

Indicators are more likely to be useful if they are understandable, quantifiable, and broadly applicable. They are likely to command attention if they capture changes of significance to many people in many places. Although indicators of local effects are not without value, they must be aggregated into some composite indicator if they are to serve broad policy purposes. Indicators are most policy-relevant if they are easily interpreted in terms of environmental trends or progress toward clearly articulated policy goals, and if their relevance is made clear (Landres 1992). In other words, indicators that convey information meaningful to decision makers and in a form these decision makers and the public can understand are more likely to be observed and acted on. Indicators are also more likely to be influential if they are few in numbers and capture key features of environmental systems in a highly condensed but understandable way. The manner in which data are aggregated to yield a small number of general indicators should be clear, especially to those who wish to understand how the indicators were developed. The reason for choosing indicators, and the selection criteria, should also be clear (Landres 1992).

Any objective ecological indicators should be expressed numerically, so that results can be compared with those of indicators in other places and times. For the indicators to command attention and be used, the data and calculations they are based on must be credible. The choice of what indicators to use and how to define them is necessarily somewhat subjective, but the procedures for measurement and calculations associated with a particular indicator, once defined, must be clearly specified, repeatable, and as free of subjective judgments as possible. Where they are unavoidable, the sources of subjectivity should be defined and identified (Landres 1992, Susskind and Dunlap 1981). For example, the Consumer Price Index and the percent of people unemployed are calculated by well-defined rules that have been agreed on, regardless of a person’s view about the value of full employment or low inflation or even the



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