Compared with conceptual definitions and acceptance of happiness as a construct, the principles and processes of measurement of happiness as a human trait is unclear.
The importance & utility of individual-level happiness is well-known.  The Buddha (650 BC) provided a diagnosis and a set of remedy to end  suffering \cite{kornfield2008dhammapada}.  Since then, happiness has been defined in different contexts and mostly in the context of utilitarian notions of happiness. For example, the Himalayan state of Bhutan uses Gross National Happiness as a metric of development, and puts an economic perspective to happiness \cite{ura2012short,di2008gross}.
But there exists no objective measurement of happiness by which one can measure and can gauge if an individual is 'genuinely' happy or has progressively registered an increase or decrease in this state is not available. What exist are scales that are based on subjective assessment of the participants based on self-reflection of the states of mind at a given point in time.