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Table 1 Sample size calculation

From: Cost and outcome of behavioural activation versus cognitive behaviour therapy for depression (COBRA): study protocol for a randomised controlled trial

Approach MICD Power Attrition rate Sample size per group*
50% BA-control effect size 1.90 90% 20% 220
50% BA-control effect size 1.90 80% 20% 160
LCI BA-control effect size 2.10 90% 20% 180
LCI BA-control effect size 2.10 80% 20% 135
Lower MCID 2.59 90% 20% 120
Lower MCID 2.59 80% 20% 90
  1. *Calculated assuming Patient Health Questionnaire 9 SD of 5.4 [33] and 1-sided 2.5% alpha using NQuery v7.0 MTE0-6, NQuery Statistical Solutions, 4500 Airport Business Park, Cork, Ireland. BA, behavioural activation; LCI, lowest confidence interval; MCID, minimum clinically important difference.