“Given the difficulty of defining individual well-being, defining (and measuring) family well-being is even more complex. One approach is simply to assume that family well-being is the sum of its parts. That is, if each individual in a family displays or reports positive well-being, the well-being of the family would be considered high. In this approach the unit of analysis is really the individual, and conclusions about the family are drawn based on data from or about individuals and their experiences. The measurement strategies would be the same as those used to measure individual well-being.
A second approach is to assume that the family is more than the sum of its parts-that family well-being is something different than simply the aggregation of data about individuals. In this approach there could be multiple units of observation or analysis including individual members, dyadic relationships, and the family as a whole (Thompson & Walker, 1982). Just as when assessing the well-being of individuals, there can be both internally- and externally-defined criteria for family well-being, all guided by implicit or explicitly stated values.”