In addition to the country-level data provided on EarthTrends, regional and classification aggregates calculated by WRI are available for most of the variables within the EarthTrends searchable database. These calculations require assignment of individual countries to specific regions or groups.

EarthTrends' classification of countries as 'developed' or 'developing' is based on designations by the Food and Agriculture Organization of the United Nations (FAO). As reported on the UN Statistics Division website, "There is no established convention for the designation of 'developed' and 'developing' countries or areas in the United Nations system. In common practice, Japan in Asia, Canada and the United States in northern America, Australia and New Zealand in Oceania, and Europe are considered 'developed' regions or areas." Developed countries tend to have high GDP’s (wealth), high literacy rates, minimal spread of poverty, and are technologically advanced.

Income classifications are derived from a system established by the World Bank. Economies are defined according to the most recent per capita Gross National Income (GNI; formerly GNP) statistics, using the World Bank Atlas method as follows: low income, $825 or less; lower middle income, $826 - $3,255; upper middle income, $3,256 - $10,065 (WRI groups lower and upper middle income into a single category-"middle income"); and high income, $10,066 or more. More information is available at World Bank website.

Regional classifications (i.e., what countries are considered part of Africa, Europe, etc.) follow standard WRI classifications.

Please see the EarthTrends "General Notes" for a full listing of the countries within each of these classifications. EarthTrends "General Notes" can be found on any variable dataset page by selecting the "View General Notes" button.