{smcl}
{* 31jan2002}{...}
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help for {hi:xsampsi}
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{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)