Fig. 2

Meta-analysis and trial sequential analysis (TSA) for quality of life, end of intervention for self-determination theory vs. control. a Meta-analysis. b TSA. The diversity-adjusted required information size (DARIS) was calculated according to a mean difference of 9 points, which is half of the observed SD of 18, alpha of 1.4%, beta of 20% (80% power), and diversity 0%. The DARIS was 186 participants. The cumulative Z-curve (blue line) breaches the boundary of futility (dotted outward sloping red lines) and the DARIS. The green dotted lines show naive conventional boundaries (alpha 5%)