I was wondering if anyone could help and/or direct on how to approach the data from a stepped-wedge cluster RCT.

I have a basic cohort stepped wedge trial data, with 3 groups of participants (clusters) and 4 data point collections (baseline, 3mths, 6 mths, 9mths)
Group/Time Baseline 3mnth 6mnth 9mnth
1 0 1 1 1
2 0 0 1 1
3 0 0 0 1
Each cluster enters the intervention phase at a sequential data point, starting with Group 1 receiving the intervention at 3 months and continuing to receive it until the end of the data collection.


1. I would like to estimate the effects on outcomes (i.e. ED presentations, use of health services, quality of life results) by comparing the Control and Intervention groups

2. The final aim is to conduct a cost-effectiveness analysis.


I think my first hurdle is in not understanding the Control and Intervention groups. How are these groups identified, as
eventually, all participants receive the Intervention.

What is the first step to take?

Thank you.
Elena