Person variables ± demographic, psychological, sociological
and physiological ± are intrinsic to the way an individual
views and responds to the symptom experience. Developmental
variables include the level of development or maturation
of an individual. When the model is used, person
variables may be expanded or contracted depending on the
symptom(s) and the population of interest.
The impact of developmental stage in the person domain is
illustrated in a study of midlife women where menopausal
symptoms affect quality of sleep as an outcome (Lee &
Taylor 1996). Premature infants may have under-treated pain