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What Are Indicators in Practice?

We are currently in an age of information dilemmas. Though data and statistics are now more accessible than ever - the result of technological advances such as satellites and the Internet - we still suffer from data gaps and information asymmetries. If anything, the new wealth of available data has obscured existing gaps and, sometimes, made it more difficult to get the right data in the right hands at the right time.

In the environmental arena in particular, where uncertainties can be high and opinions heated, important policy decisions have historically relied too heavily on "educated guesses" and referred too lightly to "hard" data. This fact has muddied choices and debates and, often, allowed critics to dismiss the severity of pollution problems or natural resource management issues.

Environmental indicators and performance indices can help fill these information gaps and clarify policy debates. As a tool spanning the "science-policy gap," which is the space between those who generate and understand environmental science and those who use, or should use, that science to make policy decisions, environmental indicators play an important role in the governing of our world, both in theory and in practice.

At their heart indicators simplify and illustrate complex information, allowing decisionmakers and key audiences to understand the state of a measured entity.

At their heart indicators simplify and illustrate complex information, allowing decisionmakers and key audiences to understand the state of a measured entity. From this simple effect many others follow: indicators are used to set baselines and goals, measure and communicate progress, compare performance across time, space, and jurisdictions, and keep managers and users accountable.

How Indicators Are Used

Around the world policy actors as varied as governments, businesses, academic institutions, and citizens' groups use indicators to assess performance, guide policy decisions, and manage progress toward goals.

Take governments as an example. In the economic arena, governments closely track their nation's performance on external, global indicators, such as the UN's Global Competitiveness Index, and on internal domestic indicators, such as the US's Consumer Price Index.

In the social arena nations track their progress on similar indices—the UN's Human Development Index (HDI), for example, or the group of indicators associated with the Millennium Development Goals (MDGs). In some cases, such as under the U.S. "Child Left Behind" program, domestic indicators for tracking progress are built into a policy from the start; in No Child Left Behind student performance scores on standardized tests served as indicators of program success as well as indicators for allocating program funding.

Indicators in the environmental arena play a similar role. Many long-standing and leading indicators of environmental performance, such as the World Wildlife Fund's Ecological Footprint, are used to monitor the state of the planet's environment on a country-by-country basis and, one hopes, drive discussions on policy priorities and progress towards policy goals. Many internal, domestic indicators, including the Environmental Quality Index of the US government's Natural Resources Conservation Service, are used to set program goals and baselines, assess progress, and allocate funding.

What are Environmental Indicators? 

Environmental indicators are metrics derived from observation of the world (i.e., environmental data) that are used to identify pressures on the environment, environmental conditions ("states," good or bad), broader impacts of environmental conditions (e.g., health outcomes), or effectiveness of policy responses to environmental problems. Examples of environmental indicators include water availability per capita (a supply indicator), airborne particulate matter concentrations in cubic meters of air (a quality indicator), or tons of fish caught per man hour of fishing effort (a stock health indicator).

An "index," on the other hand, means an aggregate of environmental indicators, usually converted to a common unit or scale. The Environmental Performance Index, for example, is a final "performance score" comprised of 10 individual indicators (e.g., water quality, air quality, etc.).

How Are Indicators Useful?

There are a number of ways in which indicators can help policy makers, and society more broadly, improve governance. Indicators can help:

Describe issues

By reducing complexity in policy-relevant ways
By answering the question "What's happening?"

Diagnose problems

By depicting trends and enabling comparisons between diverse phenomena

Discover patterns

By identifying leaders and laggards
By helping to identify best and worst practices
By targeting resources

Deliberate about solutions

By helping societies and decision-makers engage in dialogue about what kind of future they want to have
By helping ground discussion in empirical reality
By setting goal posts whose desired positions can be debated

Drive action

By helping to navigate to a desired future
By holding decisionmakers and managers accountable
By rewarding progress and punishing inaction

For a full review of the literature and theory behind environmental indicators—their potential and actual uses— see the Yale and Columbia University publication, Indicators in Practice: How Indicators are Being Used in Policy and Management Contexts (2013). Indicators in Practice case studies are available here.


The Environmental Performance Index (EPI) is constructed through the calculation and aggregation of 20 indicators reflecting national-level environmental data. These indicators are combined into nine issue categories, each of which fit under one of two overarching objectives. Click on "Learn More" to explore the complete methods.

Data Explorer

The EPI Data Explorer allows users to dynamically investigate global data: Compare environmental performance with GDP, population, land area, or other variables; create a chart that highlights all 178 ranked countries, only those in a specific region, or a custom-defined group. There's a lot more to the data than rankings, so dive in.