Data Analysis Papers
Like Wine, the TTEST Procedure Improves with Age
John Castelloe and Randy Tobias, SAS Institute, 2006
Abstract
PROC TTEST is an old reliable among SAS/STAT procedures, testing hypotheses about means of one and two normal samples. While this is a narrow class of analyses, it's an important class, with key applications in all areas of science, including clinical trials. Recent updates to the TTEST procedure make it an even more powerful tool for the statistician. The enhancements include:
- Equivalence tests, which answer not "Are the samples significantly different?" but rather "Are they significantly the same?"
- AB/BA crossover studies, a common repeated measures design for clinical trials
Perhaps the most useful new feature is the new plotting capability of PROC TTEST. It now produces univariate and comparative versions of histograms, box plots, and densities.
This paper describes these new features of PROC TTEST in SAS 9.2 and illustrates their use in a number of examples.
Statistics and Operations
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