Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: R: Sample size for non inferiority trial


From   "Carlo Lazzaro" <carlo.lazzaro@tin.it>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: R: Sample size for non inferiority trial
Date   Mon, 12 Nov 2007 17:53:04 +0100

Alvine wrote:

Dear all, 

I'd like to estimate the sample size for a non inferiority clinical trial.
We have 2 surgery techniques, A and B, and we compare quality of life score
after surgery.
For surgery A, the score is 180 (the max for this score level is 200)
We would like that the score with surgery B be not inferior to 165

Standard deviation is ~20

Is there a way to estimate sample size for non inferiority trial with Stata
?

Thank you 

Alvine Bissery

*****************************************************
Alvine BISSERY
Ingénieur statisticien 
Service de Biostatistique des Hospices Civils de Lyon 
162 Avenue Lacassagne 
69424 Lyon Cedex 03 - France 
tél: +33 4 72 11 57 55 
fax: +33 4 72 11 51 41 


Dear Alvin,

Provided that I have not overlooked something about your thread, I suppose
that the answer might sound like the following example:
----------------------begin example-----------------------
sampsi 180 165, p(.90) sd(20)

Estimated sample size for two-sample comparison of means

Test Ho: m1 = m2, where m1 is the mean in population 1
                    and m2 is the mean in population 2
Assumptions:

         alpha =   0.0500  (two-sided)
         power =   0.9000
            m1 =      180
            m2 =      165
           sd1 =       20
           sd2 =       20
         n2/n1 =     1.00

Estimated required sample sizes:

            n1 =       38
            n2 =       38

----------------------end example-----------------------
Fore more on this topic, I would take the liberty to refer you to the
following textbooks:

Juul S: An Introduction to Stata for Health Researchers. Stata Press, 2006

Peacock J, Kerry S. presenting medical statistics from proposal to
publications. Oxford University Press, 2007
HTH and Kind Regards,

Carlo


*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/


*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index