Here is the design of a clinical trial:

Official Title: An Individualized Approach to Promote Nurturing Care in Low and Middle Income Countries: a Hybrid Effectiveness/Implementation Trial of the International Guide for Monitoring Child Development

Included conditions:
- Child Development

Study Armgroups:
- {'label': 'Intervention arm', 'type': 'EXPERIMENTAL', 'description': 'Subjects from intervention clusters will receive the GMCD intervention, delivered in monthly visits to the home by frontline health workers, for 24 months. 0-12 months represents the primary effectiveness study, and 12-24 months a secondary maintenance study.', 'interventionNames': ['Behavioral: International Guide for Monitoring Child Development']}
- {'label': 'Control Arm', 'type': 'NO_INTERVENTION', 'description': 'Subjects in control clusters will continue to receive usual care from their frontline health workers. After 12 months (primary effectiveness study) control will cross into the intervention for months 12-24.'}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'International Guide for Monitoring Child Development', 'description': 'Monthly GMCD visits includes assessment of risk factors, open-ended exploration of caregiver concerns about development, assessment of functioning in seven developmental domains, and using mutual problem solving strategies to develop a nurturing care plan with the caregiver.', 'armGroupLabels': ['Intervention arm']}

Primary Outcomes:
- {'measure': 'Change in Composite Language Score at 12 months', 'description': 'Using the Bayley Scales of Infant Development, 4th Edition (BSID4), higher scores better, scale range 47-153', 'timeFrame': 'Change from 0 to 12 months'}
- {'measure': 'Change in Composite Motor Score at 12 months', 'description': 'Using the Bayley Scales of Infant Development, 4th Edition (BSID4), higher scores better, scale range 46-154', 'timeFrame': 'Change from 0 to 12 months'}
- {'measure': 'Change in Composite Cognitive Score at 12 months', 'description': 'Using the Bayley Scales of Infant Development, 4th Edition (BSID4), higher scores better, scale range 55-145', 'timeFrame': 'Change from 0 to 12 months'}

Please estimate the sample size based on the assumption: 
Assuming an intracluster correlation coefficient of 0.2 and refusals and attrition of 25%, the sample size will have 80% power to detect an overall difference of 0.3 SD on the BSID3 language composite score. The sample size is also powered to allow independent analysis of each site at a difference of 0.4 SD with 80% power.
Sample size and recruitment
        Our total sample size is 624 children in 52 clusters, n=312 (26 clusters) in India and n=312 (26 clusters) in Guatemala. Our primary effectiveness outcome is to compare the difference in mean BSID3 Scores at 12 months. Cohenâs d effect sizes of recent community-based integrated parenting interventions on childrenâs development including studies in India and Guatemala have ranged from 0.3 to 0.4 SDs.11 14â17 Assuming an intracluster correlation coefficient of 0.2 and refusals and attrition of 25%, our sample size will have 80% power to detect an overall difference of 0.3 SD on the BSID3 language composite score. The sample size is also powered to allow independent analysis of each site at a difference of 0.4 SD with 80% power.
        Research staff will obtain lists of eligible children from participating frontline workers. Study nurses will join the frontline health worker at enrollment home visits, confirm eligibility and solicit informed consent. These recruitment activities will be supplemented with phone calls or additional home visits as needed.