Amartya Sen uses his 1999 work Development as Freedom to evaluate the processes and outcomes of economic development. Having come to the conclusion that development is best summed up as the expansion of freedom, Sen examines traditional definitions and understandings of the term. He says people tend to think of freedoms as economic (the freedom to enter into market exchanges) or political (the freedom to vote and be an active citizen), and tries to understand why the definition has been so narrow hitherto. He concludes that an evaluation of true freedom must necessarily include the freedom to access social services such as healthcare, sanitation and nutrition, just as much as it must acknowledge economic and political freedoms. Evaluating the relevance of the current thinking behind development, Sen concludes that the term 'freedom' cannot simply be about income. In many ways, measuring income does not account for various "unfreedoms" (manmade or natural bars to wellbeing) that hinder development. Sen's evaluation is all the more powerful for its clarity: "The freedom-centered perspective has a generic similarity to the common concern with "quality of life."