Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: Post estimation power estimations.
From
Lars Folkestad <[email protected]>
To
"[email protected]" <[email protected]>
Subject
st: Post estimation power estimations.
Date
Sat, 15 Oct 2011 17:45:55 +0200
Evnin' list.
I have a question for you: when you do a ttest and you have no significant difference, you can estimate the group size needed for the between group differences to be significant, using SD and the differences in mean. I know this is a statistical no no - but lets save that discussion for another chain of emails.
My problem is that the between group difference is significant. When i correct for a variable, that shouldent interfere the between group difference dissaperes.
What i've done:
Xi: regress var1 var2 i.group
_group_2 p=0.45
Indicating that the Var2 adjusted var1 between group difference is no longer significant. I believe This is a power issue.
Can i aply the same logic as in ttest exemple, and if so - how to do that in Stata?
Mvh
Lars Folkestad
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/