Currently economists measure the wealth of a nation or economy by the gross domestic product,or GDP,which is a calculated value for all the products the nation produces.GDP calculations don't include the cost of externalities (see the preceding section) and,therefore,don,t truly reflect the production cost for a nation's products.Traditionally,economists have also considered a nation's overall consumption to be indicator of wealth the more resources a nation consumes,the wealthier the nation is.