The index was developed to make best possible use of information from surveys in the countries of the region, with a view to providing the region with an instrument to monitor public policies that is comparable between countries and can be applied to its entire population and used continually over the long term, as noted above. The rights-based approach describes the institutional means necessary for achieving well-being, while needs and capabilities —or functionings— are a way of describing and expressing the various constituent parts of well-being. The guaranteed exercise of rights enables people to satisfy their basic needs and function at a basic level.