The PAIREDMEANS statement performs power and sample size analyses for t tests, equivalence tests, and confidence interval precision involving paired samples.
Table 77.14 summarizes the options available in the PAIREDMEANS statement.
Table 77.16: PAIREDMEANS Statement Options
Option 
Description 

Define analysis 

Specifies an analysis of precision of the confidence interval for the mean difference 

Specifies the underlying distribution assumed for the test statistic 

Specifies the statistical analysis 

Specify analysis information 

Specifies the significance level 

Specifies the lower equivalence bound 

Specifies the null mean difference 

Specifies the null mean ratio 

Specifies the number of sides and the direction of the statistical test or confidence interval 

Specifies the upper equivalence bound 

Specify effects 

Specifies the desired confidence interval halfwidth 

Specifies the mean difference 

Specifies the geometric mean ratio, 

Specifies the two paired means 

Specify variability 

Specifies the correlation between members of a pair 

Specifies the common coefficient of variation 

Specifies the coefficient of variation for each member of a pair 

Specifies the standard deviation of each member of a pair 

Specifies the common standard deviation 

Specify sample size 

Enables fractional input and output for sample sizes 

Specifies the number of pairs 

Specify power and related probabilities 

Specifies the desired power of the test 

Specifies the type of probability for the PROBWIDTH= option 

Specifies the probability of obtaining a confidence interval halfwidth less than or equal to the value specified by the HALFWIDTH= 

Control ordering in output 

Controls the output order of parameters 
Table 77.17 summarizes the valid result parameters for different analyses in the PAIREDMEANS statement.
To define the analysis, choose one of the following parameterizations:
To specify the means, choose one of the following parameterizations:
individual means (by using the PAIREDMEANS= option)
mean difference (by using the MEANDIFF= option)
mean ratio (by using the MEANRATIO= option)
To specify the coefficient of variation, choose one of the following parameterizations:
common coefficient of variation (by using the CV= option)
individual coefficients of variation (by using the PAIREDCVS= option)
To specify the standard deviation, choose one of the following parameterizations:
common standard deviation (by using the STDDEV= option)
individual standard deviations (by using the PAIREDSTDDEVS= option)
This section summarizes the syntax for the common analyses supported in the PAIREDMEANS statement.
You can express effects in terms of the mean difference and variability in terms of a correlation and common standard deviation, as in the following statements. Default values for the DIST= , SIDES= , NULLDIFF= , and ALPHA= options specify a twosided test for no difference with a normal distribution and a significance level of 0.05.
proc power; pairedmeans test=diff meandiff = 7 corr = 0.4 stddev = 12 npairs = 50 power = .; run;
You can also express effects in terms of individual means and variability in terms of correlation and individual standard deviations:
proc power; pairedmeans test=diff pairedmeans = 8  15 corr = 0.4 pairedstddevs = (7 12) npairs = . power = 0.9; run;
You can express variability in terms of correlation and a common coefficient of variation, as in the following statements. Defaults for the DIST= , SIDES= , NULLRATIO= and ALPHA= options specify a twosided test of mean ratio = 1 assuming a lognormal distribution and a significance level of 0.05.
proc power; pairedmeans test=ratio meanratio = 7 corr = 0.3 cv = 1.2 npairs = 30 power = .; run;
You can also express variability in terms of correlation and individual coefficients of variation:
proc power; pairedmeans test=ratio meanratio = 7 corr = 0.3 pairedcvs = 0.8  0.9 npairs = 30 power = .; run;
The following statements demonstrate a sample size computation for a TOST equivalence test for a normal mean difference. Default values for the DIST= and ALPHA= options specify a normal distribution and a significance level of 0.05.
proc power; pairedmeans test=equiv_diff lower = 2 upper = 5 meandiff = 4 corr = 0.2 stddev = 8 npairs = . power = 0.9; run;
The following statements demonstrate a power computation for a TOST equivalence test for a lognormal mean ratio. Default values for the DIST= and ALPHA= options specify a lognormal distribution and a significance level of 0.05.
proc power; pairedmeans test=equiv_ratio lower = 3 upper = 7 meanratio = 5 corr = 0.2 cv = 1.1 npairs = 50 power = .; run;
By default CI= DIFF analyzes the conditional probability of obtaining the desired precision, given that the interval contains the true mean difference, as in the following statements. The defaults of SIDES= 2 and ALPHA= 0.05 specify a twosided interval with a confidence level of 0.95.
proc power; pairedmeans ci = diff halfwidth = 4 corr = 0.35 stddev = 8 npairs = 30 probwidth = .; run;