Aggregating several subjective well-being indicators into an overall index
Although the various subcomponents of subjective well-being (e.g. life evaluation, eudaimonia and affect) will convey most information when measured and reported separately, there may be demand for aggregating these into a single over-arching index of subjective well-being, particularly for the purposes of high-level communication and monitoring14 (see Stiglitz, Sen and Fitoussi, 2009, for a detailed discussion of aggregation issues in relation to well-being indicators). Where there is pressure to report just one overall headline measure, selecting only one element of subjective well-being (such as life evaluations) may neglect other important components, making aggregation across life evaluations, eudaimonia and affect an attractive prospect to those who wish to see all three components of subjective well-being reflected in headline measures.
The communication advantages in reducing different measures of subjective well-being to one number must, however, be set against a number of methodological objections. Most fundamentally, the different aspects of subjective well-being (life evaluation, affect, eudaimonia) represent distinct constructs, and it is not clear that it is possible to provide a coherent account of what an aggregate index of overall subjective well-being actually represents. Similarly, there is no clear basis for determining the relative weights to assign to different dimensions or sub-dimensions of subjective well-being. This problem is analogous to those encountered when trying to develop composite measures for other well-being outcomes, such as health or skills. Until further consideration has been given to how composites could be created, the most sensible approach may be for data producers to provide disaggregated measures - enabling users to experiment and create their own composite indices as necessary. In the meantime, where single headline figures are to be reported, life evaluations are likely to remain the focus, because they are currently the most established of the three measures in terms of their use to complement existing measures of well-being (see Chapter 1).