2.3 Randomization and treatment allocation
CMD
As primary health centers (PHC) in India serve distinct villages, we used PHCs to identify discrete geographical areas, consisting of all villages under a PHC, which was used as a unit of clustering for the trial. In Gujarat, how PHCs are distributed geographically limits the movement of people between PHCs, which helps to minimize contamination of the intervention A PHC in Gujarat covers, on average, a catchment area of 25000–30000 people which spans across 12–13 villages. At the time of the study, there were 56 PHCs in the Mehsana district, and we created 4 equal groups of 14 PHCs (A, B, C, D). These groups of clusters (A, B, C, D) were allocated to sequential steps in 5-month intervals. This study used a cross-sectional design, where outcome data is derived from different participants at each period. A random sample of 56 participants was selected from each cluster for each period. Details of blinding and contamination are mentioned elsewhere [Champions were trained to identify people with CMD based on observed symptoms described by a participant during an unstructured interview. When a Champion identified a person, they thought had a CMD and intended to provide counseling sessions to the person, then they informed their supervisor and provided details of that person. The supervisor informed these details to the project manager, who created a screening list. Screening lists of each Champion were merged to create a master screening list, which formed the sampling frame for the intervention periods. Participants were randomly selected from the master screening list using a computer-generated random method. The trained data collection staff screened the participants using the GHQ-12. The participants who scored ≥3 were recruited for the trial until the target sample of 56 participants was reached for each group of clusters and each period.Participants in the control condition were selected from electoral rolls using a systematic random sampling method with a pre-decided random start and random interval, with every 