Ecology is often involved in political economy, because human activity is one of the single largest effects on the environment, and because it is the suitability of the environment for human beings which is one of the central concerns of most human beings. The ecological effects of economic activity on the environment have spurred the creation of a great deal of research studying means of changing the incentives balance of the market economy. This work is particularly controversial in its interaction with economics, since it questions the fundamental econometric assumptions of market economics and their basic validity.