Objective: The delivery of an intervention is a critical step in intervention evaluation research. The intervention should be implemented as-designed in order to make valid inferences about its effectiveness in producing the expected outcomes. Strategies for enhancing the proper delivery of the intervention have been suggested. These include intensive training of the person responsible for delivering the intervention and monitoring the actual delivery of the intervention. While these strategies are useful, they may not be applicable when the clients are actively involved in the intervention implementation, on their own, and under the conditions of everyday life. Under these circumstances, additional strategies are required to determine the extent to which the clients performed the planned and prescribed intervention activities. Design: This paper (a) addresses the delivery of the intervention under real-world conditions, (b) provides examples of strategies applicable to real-world conditions and illustrates their advantages with examples, and (c) examines how these factors influence the intervention effectiveness. The additional strategies and examples are taken from a program of research aimed at evaluating the effectiveness of a behavioral intervention for managing persistent insomnia. The studies used to provide examples incorporate an experimental design with repeated measures. One study focuses on older adults with primary persistent insomnia while the second project includes persons 21 and older with both primary and secondary persistent insomnia. All participants live independently in the community. Intervention and Strategies: Participants receive multi-component or single component cognitive-behavioral treatment for persistent insomnia in a group format for 4 weekly sessions. An additional 2 weeks of treatment is delivered by telephone to the participant. The participants’ implementation of the cognitive-behavioral intervention is monitored in two ways: 1) by counting the number of group sessions attended and phone contacts made by the participants with the therapist (i.e., dose of the intervention); and 2) by estimating the extent of adherence to the prescribed intervention activities. Clients are requested to keep a diary of their sleep-wake schedule and of the activities they performed. Conclusions and Implications: Intervention delivery is represented by the treatment dose received and the participants’ adherence to the intervention. An issue when implementing an intervention under real-world conditions is the participant’s ability, rather than the intervener’s ability, to maintain consistent implementation. In this situation, researchers are called upon to develop new methods for monitoring implementation. A lack of consistency in treatment implementation by participants will result in variability in outcome achievement within the experimental group. The result is increased within-group variance and, subsequently, decreased power to detect significant intervention effects. Developing strategies to ensure consistent implementation and representing the intervention delivery in the statistical analysis increases power and provides an opportunity to examine dose-response effects.
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