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Re: st: difference between -test- and -contrast- in Statat 12
From
Richard Williams <[email protected]>
To
[email protected]
Subject
Re: st: difference between -test- and -contrast- in Statat 12
Date
Thu, 25 Aug 2011 23:53:51 -0400
At 10:15 PM 8/25/2011, Ricardo Ovaldia wrote:
I am using the new -contrast- command in Stata 12 to test a contrast
after ANOVA and I get different p-values than when using -test-
although the marginal means are the same.
Confirming my earlier theory (I think): The value of both the F and
the chi-square test stat is .72867669. I am one of 3 people in the
world who still uses Stataquest, so using its handy calculator functions,
. tablesq F 1 63 .72867669
F(1,63) = .72867669
Pr(F <= .72867669) = 0.6035
Pr(F >= .72867669) = 0.3965
. tablesq X 1 .72867669
X(1) = .72867669
Pr(X <= .72867669) = 0.6067
Pr(X >= .72867669) = 0.3933
Those are the same p values you reported.
As a sidelight, I could probably let Stataquest rest in peace if
Stata just had a nice calculator menu like Stataquest does. I know
there are commands out there that do the same thing but it is too
much trouble to hunt around for them.
-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
EMAIL: [email protected]
WWW: http://www.nd.edu/~rwilliam
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