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