It is important to include outcome measures that are closely related to the goals of intervention.
Zarit et al. (1998) developed a careful conceptual model that notes the kinds of variables most likely to be improved by adult day care--e.g. measures of appraisals of primary stressors, such as feelings of role captivity and overload, and more distal variables affected by many factors besides intervention, such as caregiver well-being.
For studies targeting improved management of behavioral problems or increased caregiver knowledge, there should be careful measurement of these constructs.
Zarit, S. H., et al. 1998. Stress reduction for family caregivers: Effects of adult day care use. Journal of Gerontology, 53B(5): S267-77.