Design, Monitoring, and Analysis of Clinical Trials

February, 2003

Session 3: 45

Schedule of Analyses

Use of constrained families is necessary because critical values are dependent upon exact schedule

In Unified Family, boundary at first analysis is affected by timing of later analyses

Compare boundary at first analysis when timing of second analysis differs:

·`a’ boundary: -0.0743 versus -0.0740

·‘d’ boundary: 0.5744 versus 0.5713

Must constrain first boundaries at the levels actually used, and then use parametric form for future analyses