GNH index is used to measure the collective happiness and well being of a population. How is it calculated? Is it a substitute for gross domestic products (GDP)?
You can find a good description here: https://ophi.org.uk/policy/national-policy/gross-national-happiness-index/
The aim is to get an indicator of well-being alternative to the GDP. In practical terms, there are many objections to this sort of measure. Other more popular are in line with the Human Development Index ( http://hdr.undp.org/en/content/human-development-index-hdi ) and its expansions in recent years. Summarising too much, one can say that alternative measures to GDP per capita suffer from subjectivity in the selection and aggregation of dimensions. In the case of happiness, it is possible to mention also human beings' ability to adapt. The Stiglitz-Sen-Fituossi Report on measuring economic performance and social progress might be an essential reading for you ( https://ec.europa.eu/eurostat/documents/118025/118123/Fitoussi+Commission+report ), as well as the Atkinson Review on how to measure the output of the public sector ( https://pdfs.semanticscholar.org/aa51/5465288bbe305ccf2c79b18450344626e78e.pdf ).