Randomized controlled trial design and power analysis

Design robust RCT with appropriate statistical power. Study design: 1. Define primary outcome clearly (e.g., change in depression score). 2. Choose randomization method (simple, block, stratified). 3. Blinding strategy (single, double, triple-blind where possible). 4. Control group selection (placebo, wait-list, treatment-as-usual). Power analysis using G*Power: 1. Set α = 0.05, power = 0.80. 2. Estimate effect size from pilot data or literature (Cohen's d). 3. Calculate minimum sample size, add 20% for dropouts. Example: t-test, medium effect (d=0.5), requires n=64 per group, with dropout n=80 per group. Randomization tools: Research Randomizer, RedCap. Registration: ClinicalTrials.gov before recruitment. Monitor for interim analyses and stopping rules.