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
| Graphics Output |
This section describes the use of ODS for creating graphics with the SEQDESIGN procedure. To request these graphs, ODS Graphics must be enabled and you must specify the associated graphics options in the PROC SEQDESIGN statement. Except for the PLOTS=BOUNDARY option, where a detailed boundary plot is generated for each design separately, each option produces a plot for all designs together. For more information about ODS Graphics, see Chapter 21, Statistical Graphics Using ODS.
Sequential ASN Plot
The PLOTS=ASN option displays the average sample numbers (expected sample sizes for nonsurvival data or expected numbers of events for survival data) under various hypothetical references. The average sample numbers are connected for each design, and these connected curves for all designs are displayed in the "Sequential ASN Plot" graph.
For a one-sided design, average sample numbers under the hypothetical references 
are displayed, where 
are the values specified in the CREF= option and 
is the alternative reference. The horizontal axis displays the values of these hypothetical references.
For a two-sided design, average sample numbers under each of the hypothetical references 
and 
are displayed, where 
and 
are the lower and upper alternative references, respectively. The horizontal axis displays 
values for lower hypothetical references and values for upper hypothetical references .
Note that for a symmetric two-sided design, only average sample numbers under the hypothetical references are derived.
Sequential Boundary Plot
The PLOTS=BOUNDARY option displays boundary values and the acceptance and rejection regions at each stage for each design separately in the "Detailed Boundary Information" graph. The BOUNDARYSCALE= option is used to specify the scale of the boundaries on the vertical axis. The keywords MLE, SCORE, STDZ, and PVALUE in the BOUNDARYSCALE= option correspond to the boundary with the MLE scale, score statistic scale, standardized normal 
scale, and 
-value scale, respectively.
The stage numbers are displayed on the horizontal axis. In addition, the HSCALE= option in the PLOTS=BOUNDARY option can be used to specify the scale on the horizontal axis. The keywords INFO and SAMPLESIZE in the HSCALE= option correspond to the information levels and sample sizes, respectively.
Combined Sequential Boundary Plot
The PLOTS=COMBINEDBOUNDARY option displays boundary values. The boundary values are connected for each boundary in each design, and these connected curves for all designs are displayed in the "Sequential Boundary Information" graph. The BOUNDARYSCALE= option is used to specify the scale of the boundaries on the vertical axis. The keywords MLE, SCORE, STDZ, and PVALUE in the BOUNDARYSCALE= option correspond to the boundary with the MLE scale, score statistic scale, standardized normal scale, and -value scale, respectively.
The HSCALE= option in the PLOTS=COMBINEDBOUNDARY option can be used to specify the scale on the horizontal axis. The keywords INFO, SAMPLESIZE, and STAGE in the HSCALE= option correspond to the information levels, sample sizes, and stage numbers, respectively.
Sequential Error Spending Plot
The PLOTS=ERRSPEND option displays the cumulative error spending at each stage on each boundary in the "Sequential Error Spending Plot" graph. A legend table uses the design labels to identify the curves for the corresponding design in the plot. Another legend table uses symbols to identify boundaries in the plot.
Sequential Power Plot
The PLOTS=POWER option displays the powers under various hypothetical references. The powers are connected for each design, and these connected curves for all designs are displayed in the "Sequential Power Plot" graph.
For a one-sided design, powers under hypothetical references are displayed, where are the values specified in the CREF= option and is the alternative reference. The horizontal axis displays the values of these hypothetical references.
For a two-sided design, powers under hypothetical references and are displayed, where and are the lower and upper alternative references, respectively. The horizontal axis displays values for lower hypothetical references and values for upper hypothetical references .
Note that for a symmetric two-sided design, only powers under hypothetical references are derived.