Opportunity to choose is measured by absence of restrictions in economics, political and personal life. Capability to choose is measured by information and inclination to go one's own way. Happiness is conceived as the overall appreciation of one's life as a whole. Average happiness in nations is measured by responses to questions on the matter in representative surveys. Data on both freedom and happiness is available for 48 nations in the early 1990's.
Analysis shows first of all positive correlation between freedom and happiness.
Yet closer analysis reveals that freedom and happiness do not always concur. Freedom is positively related to happiness among rich nations, but not among poor nations. Apparently, freedom does not pay in poverty. Further, freedom is related to happiness only when 'opportunity' and 'capability' coincide. A notable exception is economic freedom.