Jaye Brown wrote:
I am trying to analyse a 3-way anova and look at the 3 way interactions
using test and got the following results.
. test _coef[m[1]*s[2]*i[2]] = _coef[m[1]*s[2]*i[3]]
( 1) m[1]*s[2]*i[2] - m[1]*s[2]*i[3] = 0
F( 1, 162) = 4.24
Prob > F = 0.0412
. test _coef[m[2]*s[2]*i[2]] = _coef[m[2]*s[2]*i[3]]
( 1) m[2]*s[2]*i[2] - m[2]*s[2]*i[3] = 0
Constraint 1 dropped
I am confused as to why I get the message "Constraint 1 dropped" and does
this mean that I cannot estimate this interaction term?
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It could be signaling that one or more of the involved coefficients has
been dropped for model identifiability. Try typing -anova ,
egress-. -anova- typically drops the highest level of a factor (just like
SAS's PROC GLM and PROC ANOVA), unless you change it with -char
varname[omit] #-.
It's just a guess, but are you sure that your test is really testing the
hypothesis that you intend to test? -anova , regress- or -anova , symbolic-
would be informative for that, too. I'd recommend the same thing to Janet
Pol, who posted an analogous contrast earlier this week.
Joseph Coveney
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