The SEQDESIGN Procedure
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Overview
- Getting Started
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Syntax
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Details
Fixed-Sample Clinical Trials One-Sided Fixed-Sample Tests in Clinical Trials Two-Sided Fixed-Sample Tests in Clinical Trials Group Sequential Methods Statistical Assumptions for Group Sequential Designs Boundary Scales Boundary Variables Type I and Type II Errors Unified Family Methods Haybittle-Peto Method Whitehead Methods Error Spending Methods Acceptance (beta) Boundary Boundary Adjustments for Overlapping Lower and Upper beta Boundaries Specified and Derived Parameters Applicable Boundary Keys Sample Size Computation Applicable One-Sample Tests and Sample Size Computation Applicable Two-Sample Tests and Sample Size Computation Applicable Regression Parameter Tests and Sample Size Computation Aspects of Group Sequential Designs Summary of Methods in Group Sequential Designs Table Output ODS Table Names Graphics Output ODS Graphics Acknowledgments
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Examples
Creating Fixed-Sample Designs Creating a One-Sided O’Brien-Fleming Design Creating Two-Sided Pocock and O’Brien-Fleming Designs Generating Graphics Display for Sequential Designs Creating Designs Using Haybittle-Peto Methods Creating Designs with Various Stopping Criteria Creating Whitehead’s Triangular Designs Creating a One-Sided Error Spending Design Creating Designs with Various Number of Stages Creating Two-Sided Error Spending Designs with and without Overlapping Lower and Upper beta Boundaries Creating a Two-Sided Asymmetric Error Spending Design with Early Stopping to Reject H0 Creating a Two-Sided Asymmetric Error Spending Design with Early Stopping to Reject or Accept H0
- References
| Boundary Variables |
The boundaries created in group sequential trials depend on the type of the alternative hypothesis and the early stopping criterion. Table 80.5 shows the boundaries created with various design specifications.
Specifications |
Boundary Variables |
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Alternative |
Lower |
Upper |
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Hypothesis |
Early Stopping |
Alpha |
Beta |
Beta |
Alpha |
Lower |
Accept |
X |
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Reject |
X |
||||
Accept/Reject |
X |
X |
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Upper |
Accept |
X |
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Reject |
X |
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Accept/Reject |
X |
X |
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Two-sided |
Accept |
X |
X |
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Reject |
X |
X |
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Accept/Reject |
X |
X |
X |
X |
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Up to four boundaries can be generated in a group sequential design:
the upper
boundary, to reject the null hypothesis for the upper alternative the upper
boundary, to accept the null hypothesis with an upper alternative the lower
boundary, to accept the null hypothesis with a lower alternative the lower
boundary, to reject the null hypothesis for the lower alternative
For a two-sided design, the null hypothesis is accepted only if both the hypothesis is accepted with an upper alternative and the hypothesis is accepted with a lower alternative.
For a one-sided design with a lower alternative, only the lower boundaries are created. Similarly, for a one-sided design with an upper alternative, only the upper boundaries are created. For example, Figure 80.10 shows the boundary plot for a one-sided test with an upper alternative.
Figure 80.10 corresponds to a one-sided sequential design with early stopping to reject or accept the null hypothesis. For a sequential test with early stopping only to reject the null hypothesis, there are no acceptance boundary values at interim stages. The acceptance boundary value and its associated acceptance region are displayed only at the final stage. Similarly, for a sequential test with early stopping only to accept the null hypothesis, there are no rejection boundary values at interim stages. The rejection boundary value and its associated rejection region are displayed only at the final stage.
For a two-sided design, both the lower and upper boundaries are created. For a design with early stopping to reject the null hypothesis, boundaries are created. Similarly, for a design with early stopping to accept the null hypothesis, boundaries are created. For a design with early stopping to accept or reject the null hypothesis, both the and boundaries are created.
For example, Figure 80.11 shows the boundary plot for a two-sided test.
Figure 80.11 corresponds to a two-sided sequential design with early stopping to reject or accept the null hypothesis. For a sequential test with early stopping only to reject the null hypothesis, there are no acceptance boundary values at interim stages. The acceptance boundary value and its associated acceptance region are displayed only at the final stage. Similarly, for a sequential test with early stopping only to accept the null hypothesis, there are no rejection boundary values at interim stages. The rejection boundary value and its associated rejection region are displayed only at the final stage.