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
| Applicable Boundary Keys |
In the SEQDESIGN procedure, the BOUNDARYKEY= option in the DESIGN statement specifies the types of errors to be maintained for the design. Table 80.9 lists applicable boundary keys for designs that use unified family and Haybittle-Peto methods, designs that use error spending methods, and designs that use the Haybittle-Peto method only.
Specified Parameters |
Boundary Keys |
||||
Method |
(Alt Ref – Max Info) |
Alpha |
Beta |
None |
Both |
Unified |
X |
X |
X |
||
Unified/Haybittle-Peto |
X |
X |
X |
||
Error spending |
X |
X |
X |
||
Haybittle-Peto |
X |
X |
X |
X |
|
Unified/Haybittle-Peto |
X |
||||
Error spending |
X |
||||
Haybittle-Peto |
X |
||||
Note that the symbol "X" under "(Alt Ref – Max Info)" indicates that both the alternative reference and maximum information are specified, and the method "Unified/Haybittle-Peto" indicates that both the unified method and the Haybittle-Peto method are used in the same design.
If the ALTREF= and MAXINFO= options are both specified, then Type I and Type II error probability levels cannot be met simultaneously if both error probabilities are specified. The BOUNDARYKEY=ALPHA option maintains the Type I error probability level 
and derives Type II error probability 
. The BOUNDARYKEY=BETA option maintains the Type II error probability level and derives Type I error probability .
If the Haybittle-Peto method is used for all boundaries, the BOUNDARYKEY=NONE option uses the specified boundary value (STOP=REJECT or STOP=BOTH) and the specified boundary value (STOP=ACCEPT) at the final stage for the design.
If the ALTREF= and MAXINFO= options are not both specified, the BOUNDARYKEY=BOTH option derives boundary values that maintain both Type I and Type II error probability levels.
Table 80.10 lists applicable boundary keys for a design that uses Whitehead methods.
Specified Parameters |
Boundary Keys |
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Early Stopping |
(Alt Ref – Max Info) |
Tau |
Alpha |
Beta |
None |
Both |
Reject |
X |
X |
X |
X |
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Accept |
X |
X |
X |
X |
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Reject/Accept |
X |
0.25 |
X |
X |
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Reject |
X |
X |
||||
Accept |
X |
X |
||||
Reject/Accept |
0.25 |
X |
X |
X |
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Note that the symbol "X" under "(Alt Ref – Max Info)" indicates that both alternative reference and maximum information are specified.
If the ALTREF= and MAXINFO= options are both specified, then Type I and Type II error probability levels cannot be achieved simultaneously if both are specified. the BOUNDARYKEY=ALPHA option maintains the Type I error probability level and derives Type II error probability . The BOUNDARYKEY=BETA option maintains the Type II error probability level and derives the Type I error probability .
If the ALTREF= and MAXINFO= options are not both specified, then for a design with the STOP=REJECT or STOP=ACCEPT option, the BOUNDARYKEY=BOTH option derives boundary values that maintain both Type I and Type II error probability levels. If the STOP=BOTH option is specified, Whitehead’s triangular method produces boundaries with approximate Type I and Type II error probabilities. The BOUNDARYKEY=NONE option specifies no adjustment to these boundaries. The BOUNDARYKEY=ALPHA and BOUNDARYKEY=BETA options maintain the Type I error probability level and Type II error probability level , respectively, by adjusting boundary values at the final stage.