The SEQDESIGN Procedure 
PROC SEQDESIGN Statement 
Table 78.1 summarizes the options in the PROC SEQDESIGN statement.
Option 
Description 

Design Parameters 

ALTREF= 
Specifies the alternative reference 
BOUNDARYSCALE= 
Specifies the statistic scale for the boundary 
MAXINFO= 
Specifies the maximum information level 
Table Output 

ERRSPEND 
Displays the cumulative error spending at each stage 
PSS 
Displays powers and expected sample sizes 
STOPPROB 
Displays expected cumulative stopping probabilities 
Graphics Output 

PLOTS=ASN 
Displays the expected sample numbers plot 
PLOTS=BOUNDARY 
Displays the detailed boundary plot 
PLOTS=COMBINEDBOUNDARY 
Displays the combined boundary plot 
PLOTS=ERRSPEND 
Displays the error spending plot 
PLOTS=POWER 
Displays the powers plot 
By default, the SEQDESIGN procedure displays tables of design information, method information, and boundary information for each specified design. If the ODS GRAPHICS ON statement is specified, it also displays a detailed boundary plot.
In addition, you can use output options to display output tables such as expected cumulative stopping probability at each stage under various hypothetical references. If the ODS GRAPHICS ON statement is specified, you can also use output options to display plots such as powers and expected sample sizes under various hypothetical references.
The following options can be used in the PROC SEQDESIGN statement to derive boundary values for all sequential designs in the procedure. They are listed in alphabetical order.
specifies the alternative reference—that is, the hypothetical reference under the alternative hypothesis at which the power is computed. The LOWER= and UPPER= options are applicable only for a twosided design with different lower and upper alternative references.
For a onesided design, is the lower alternative reference and is the upper alternative reference. For a twosided design, the specified and are the lower and upper alternative references, respectively. If the LOWER= option is not specified, , and if the UPPER= option is not specified, .
The specification of the ALTREF= option depends on the hypothesis used in the clinical trial. For example, suppose the null hypothesis with an alternative hypothesis is used to compare two binomial populations, . Then is the proportion difference under if , and is the log odds ratio under if .
If the ALTREF= option is not specified, the alternative reference can also be specified or derived in the SAMPLESIZE statement. If is specified or derived in the SAMPLESIZE statement, and are the lower and upper alternative references, respectively.
Note that if the SAMPLESIZE statement is specified with a twosided design, the sample sizes derived by using the lower and upper alternatives might be different. If is specified or derived in the SAMPLESIZE statement, it is used to compute the sample sizes. Otherwise, the specified in the ALTREF= option is used.
specifies the scale for the statistic that is displayed in the boundary table and boundary plots. The keywords MLE, SCORE, STDZ, and PVALUE correspond to the boundary with the maximum likelihood estimate scale, the score statistic scale, the standardized normal scale, and the value scale, respectively. The default is BOUNDARYSCALE=STDZ.
With the BOUNDARYSCALE=MLE or BOUNDARYSCALE=SCORE option, the maximum information must be either explicitly specified with the MAXINFO= option or derived in the SEQDESIGN procedure to provide the necessary information level at each stage to compute the boundary values. See the section Boundary Scales for a detailed description of the statistic scale for the boundary values.
Note that for a twosided design, the value scale displays the onesided fixedsample value under the null hypothesis with a lower alternative hypothesis.
specifies the maximum information level for the design. If the MAXINFO=option is specified and the alternative reference is either specified explicitly with the ALTREF= option or derived from the SAMPLESIZE statement, then the Type I and Type II error probability levels cannot be met simultaneously. In this case, the ALPHA= option in the DESIGN statement is applicable only with the BOUNDARYKEY=ALPHA option (which is the default) in the DESIGN statement, and the Type II error probability is derived. The BETA= option in the DESIGN statement is applicable only with the BOUNDARYKEY=BETA option in the DESIGN statement, and the Type I error probability is derived.
The following options can be used in the PROC SEQDESIGN statement to display addition table output. They are listed in alphabetical order.
displays the error spending at each stage for each boundary in the design.
displays powers and expected sample sizes under various hypothetical references, where the numbers .
For a onesided design, the power and expected sample sizes under hypotheses are displayed, where is the alternative reference and are the values specified in the CREF= option.
For a twosided design, the power and expected sample sizes under hypotheses and are displayed, where and are the lower and upper alternative references, respectively. The default is CREF= 0 0.5 1.0 1.5.
Note that for a symmetric twosided design, only the power and expected sample sizes under hypotheses are derived. See the section Type I and Type II Errors for a detailed description of the power computation. See the section Powers and Expected Sample Sizes for a detailed description of the expected sample size computation.
displays expected cumulative stopping probabilities under various hypothetical references, where the numbers .
For a onesided design, expected cumulative stopping probabilities at each stage under hypotheses are displayed, where is the alternative reference and are the values specified in the CREF= option.
For a twosided design, expected cumulative stopping probabilities at each stage under hypotheses and are displayed, where and are the lower and upper alternative references, respectively. Note that for a symmetric twosided design, only expected cumulative stopping probabilities under hypotheses are derived. The default is CREF= 0 0.5 1.0 1.5.
This section describes the options for using ODS Graphics with the SEQDESIGN procedure to create plots. To request these graphs, you must specify the ODS GRAPHICS ON statement in addition to the following options in the PROC SEQDESIGN statement. For more information about the ODS GRAPHICS statement, see Chapter 21, Statistical Graphics Using ODS.
The following options can be used in the PROC SEQDESIGN statement to display graphs with ODS Graphics. They are listed in alphabetical order.
specifies options that control the details of the plots. The default is PLOTS=BOUNDARY. The global plot option ONLY suppresses the default plots and displays only plots specifically requested.
The plot request options are as follows.
produces all appropriate plots.
displays a plot of the average sample numbers (expected sample sizes for nonsurvival data or expected numbers of events for survival data) under various hypothetical references, where the numbers . These average sample numbers are displayed as percentages of the average sample numbers for the corresponding fixedsample design.
For a onesided design, expected sample numbers under hypotheses are displayed, where is the alternative reference and are the values specified in the CREF= option.
For a twosided design, expected sample numbers under hypotheses and are displayed, where and are the lower and upper alternative references, respectively. Note that for a symmetric twosided design, only the average sample numbers under hypotheses are derived. The default is CREF= 0 to 1.5 by 0.01.
displays a plot of the resulting sequential boundaries with the acceptance and rejection regions for each design. Either the information level (HSCALE=INFO) or the sample size (HSCALE=SAMPLESIZE) is displayed on the horizontal axis. If the maximum information is not available for the design, the information in percentage of its corresponding fixedsample design are used in the plot. The stage number for each stage is displayed inside the plot. The default is HSCALE=INFO.
If the HSCALE=SAMPLESIZE option is specified. the SAMPLESIZE statement must also be specified. The options MODEL=INPUTNEVENTS, MODEL=TWOSAMPLESURVIVAL, and MODEL=PHREG in the SAMPLESIZE statement indicate survival data. For a sample that does not contain survival data, the sample size at each stage is displayed on the horizontal axis. For survival data, the number of events is displayed on the horizontal axis at each stage. The critical values for the corresponding fixedsample design are also displayed in the plot.
displays a plot of the resulting sequential boundaries for all designs simultaneously. You can display the information level (HSCALE=INFO), the sample size (HSCALE=SAMPLESIZE), or the stage number (HSCALE=STAGE) on the horizontal axis. The default is HSCALE=INFO. With HSCALE=INFO, if the maximum information is not available for the design, then the information in percentage of its corresponding fixedsample design is used in the plot.
If the HSCALE=SAMPLESIZE option is specified, the SAMPLESIZE statement must also be specified. The options MODEL=INPUTNEVENTS, MODEL=TWOSAMPLESURVIVAL, and MODEL=PHREG in the SAMPLESIZE statement indicate survival data. For a sample that does not contain survival data, the sample size at each stage is displayed on the horizontal axis. For survival data, the number of events is displayed on the horizontal axis at each stage.
displays a plot of the error spending for all sequential boundaries in the designs simultaneously. You can display the information level (HSCALE=INFO) or the stage number (HSCALE=STAGE) on the horizontal axis. With HSCALE=INFO, the information fractions are used in the plot. The default is HSCALE=STAGE.
suppresses all plots.
displays a plot of the power curves under various hypothetical references, where the numbers .
For a onesided design, powers under hypotheses are displayed, where is the alternative reference and are the values specified in the CREF= option.
For a twosided design, powers under hypotheses and are displayed, where and are the lower and upper alternative references, respectively. Note that for a symmetric twosided design, only powers under hypotheses are derived. The default is CREF= 0 to 1.5 by 0.01.
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