Sample study design: Phases of intervention development by area of focus (adapted from Bowen at al 2009)³

	Intervention development phase
	Can it work?	Does it work	Will it work
Area of focus	Is there some evidence that intervention X might work?	Is there some evidence that X might be efficacious under actual conditions, compared to whatever other practices might already be in place instead?	Will it be effective in real life contexts, settings and cultures/populations that might adopt the intervention as practice?
Acceptability	Focus groups with target population participants to understand how this intervention would fit in with their daily-life activities.	An RCT to compare the satisfaction of the intervention group to that of a control group that does not receive the intervention.	A population based survey before, during and after implementation of a policy intervention. A cohort study comparing the actual use of facilities with and without the intervention over time.
Demand	Survey to determine whether people in the target population would use the intervention to guide their behavioural choices.	Pre–post intervention survey design to compare frequency of use and patterns of use across different populations.	Post-only design with multiple surveys over time to test reactions to the intervention in a new population.
Implementation	Pre–post design to evaluate whether the intervention can be deployed in any clinical or community context, using focus groups as the method of evaluation.	Different types of trial designs (pragmatic, stepped-wedge, adaptive design) to test whether the intervention can be implemented in different clinical settings or community contexts: Using surveys and observations to compare practices and outcomes before and after interventions; using focus groups and in-depth interviews to further explain what works during the intervention processes.
Practicality/cost	Small-scale demonstration study to examine the predicted cost, burden, and benefit because of appropriate and intensity, frequency, duration of the intervention, using key-informant interviews to gather data.	Cost-effectiveness analysis combined with in-depth interviews with community leaders or other stakeholders to determine how easily the intervention was used in the health system.	Cost analyses with in-depth interviews with providers to identify potential areas of concern during implementation.
Adaptation	FGD, key informant interviews to drive the adaption of the intervention. Quasi-experimental design using pre- and post-surveys to examine the effects of the adapted intervention in communities.	Experiment using adaptive design to examine whether an effective intervention continues to show evidence of efficacy once modified and implemented in a practice context.	Small-scale experiment testing appropriate intensity, frequency, and duration of the modified intervention, or intervention for the new target population.
Integration	Pre–post design to observe the extent to which people in the target setting are using the new intervention activities and with what costs and benefits to their other responsibilities.	Prospective longitudinal study to identify the sustainability of a recently tested package of intervention activities.	Annual monitoring of important systems to measure outcomes across years.
Expansion	Quasi-experimental, pre–post design using interviews with key informants to determine how well an expanded version of an intervention is perceived to work after implementation.	Uncontrolled pre–post study to test new, enhanced the version of a previously tested intervention.	Continued monitoring to identify any decay of intervention effects after implementation.