Definitional issues that affect the measurement of quality of life (QOL) in
health care research are discussed. In reviewing a broad sample of health-
and disability-related QOL studies, the authors note several characteristi
cs in which respective approaches to measurement differ: (a) In various mea
surement tools, QOL has been located either within the insider's (i.e., the
person being measured) judgment of the "goodness" of his or her life or ou
tside this judgment. (b) The insider's and/or outsider's values may hold sw
ay in deciding the elements of life that are relevant to QOL within the mea
surement process, and in rating the degree of "goodness" of these life doma
ins. (c) QOL models incorporate domains of items varying in breadth and spe
cificity; and they take either a negative or neutral view of functioning. (
d) QOL models vary in their complexity, type of linkage between components,
and inclusion (or not) of both the insider's judgment and external predict
ors of QOL. These distinctions are used by the authors in recommending appr
oaches to QOL measurement suitable for health care research aimed at outcom
e assessment and description of populations.