Intervention

Intervention research examines the effects of an intervention on an outcome of interest. The primary purpose of intervention research is to engender a desirable outcome for individuals in need (e.g., reduce depressive symptoms or strengthen reading skills). As such, intervention research might be thought of as differing from prevention research, where the goal is to prevent a negative outcome from occurring, or even from classic laboratory experimentation, where the goal is often to support specific tenets of theoretical paradigms. Assessment of an intervention's effects, the sine qua non of intervention research, varies according to study design, but typically involves both statistical and logical inferences.

The hypothetical intervention study presented next is used to illustrate important features of intervention research. Assume a researcher wants to examine the effects of parent training (i.e., intervention) on disruptive behaviors (i.e., outcome) among preschool-aged children. Of 40 families seeking treatment at a university-based clinic, 20 families were randomly assigned to an intervention condition (i.e., parent training) and the remaining families were assigned to a (wait-list) control condition. Assume the intervention was composed of six, 2-hour weekly therapy sessions with the parent(s) to strengthen theoretically identified parenting practices (e.g., effective discipline strategies) believed to reduce child disruptive behaviors. Whereas parents assigned to the intervention condition attended sessions, parents assigned to the [Page 631]control condition received no formal intervention. In the most basic form of this intervention design, data from individuals in both groups are collected at a single baseline (i.e., preintervention) assessment and at one follow-up (i.e., postintervention) assessment.