Design, Monitoring, and Analysis of Clinical Trials

February, 2003

Session 2: 51

Stopping Rules

General stopping rule

Maximum of four boundaries

·‘d’ boundary: upper outer boundary

·‘c’ boundary: upper inner boundary

·‘b’ boundary: lower inner boundary

·‘a’ boundary: lower outer boundary

Early stopping

·Tn greater than ‘d’ boundary

·Tn between ‘b’ and ‘c’ boundaries

·Tn less than ‘a’ boundary