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Modules/ado/plus/x/xsampsi.hlp

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+{smcl}
+{* 31jan2002}{...}
+{hline}
+help for {hi:xsampsi}
+{hline}
+
+{title:Sample size for AB/BA cross-over trials with continuous measures}
+
+This program will compute the required sample size for a simple crossover
+trial, that is AB/BA, or two-period two-treatment cross-over. It will
+estimate the power for a given sample size, too.
+
+You must specify:
+alpha  required significance level
+beta   1-power
+delta  the difference between treatment arms
+stddev the standard deviation of this difference
+
+You can specify:
+n      different sample sizes, for which power will be computed
+
+Requirements
+You must install the package nct ({help nct}) for this program to work. 
+
+Comments
+This program essentially duplicates step by step the method that is 
+given in Stephen Senn, "Cross-over trials in clinical research", 1993, 
+on page 217. It is almost the same as a one-sample t-test for the 
+difference between treatment, except that this method uses the non-central 
+t-distribution, which gives you more accurate answers.
+
+The variables are assumed to be normally distributed.
+
+
+See also:
+{help sampsi}, {help studysi}
+
+Written by Jan Brogger (jan.brogger@med.uib.no)
+