st: RE: RE: sampsize formula

[Sara Borelli <sborelli@impaqint.com>]

Thank you Sarah
The problem is that we do not have access to the manuals right now, but the reference helps a lot
thanks

Sara Borelli, Ph.D.
Research Associate



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-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Sarah Edgington
Sent: Thursday, November 03, 2011 3:36 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: sampsize formula

Do you have access to the Stata base reference manuals?
Typically the manuals contain detailed information on the formulas used to
implement a command.  The manual entry for -sampsi- is no exception. It's in
the section titled "Methods and formulas" near the end of the entry.
Hope that helps.
-Sarah

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Sara Borelli
Sent: Thursday, November 03, 2011 12:12 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: sampsize formula

  
Hello Statalist members,
 
I would like to know the exact formula beyond the sampsi command to
calculate the sample size of two groups using comparison of means :
 
sampsi     m1  m2,  sd1()  sd2()  power ()  alpha() 
 
the output gives me the sample size of the two groups, n1 and n2, but I
would need the exact mathematical formula
 
Thanks for any suggestion
Sara Borelli



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