--- Joseph Coveney <[email protected]> wrote:
>> That the medians of the pooled data are identical
> wouldn't bother me so much as
> the difference between the asymptotic and
> permutation p-values with 256 dams.
>
> Take a look at what -xtreg percent mm, i(dam) fe-
> gives you (and also take a
> look at, say, -pnorm- on the residuals, for
> starters). I'm guessing that
> -xtreg, fe- (which would have been my first choice
> with this design) gives you
> the same take-home message as what -vaneltern- does.
Yes, I first used -xtreg- and obtained a p-value of
0.018. Although the residual plot did not look to bad
using -pnorm-, they look bad on the -qnorm- plot. I
was concerned that I was not meeting the normality
assumption, therefore I opted to use a non-parametric
test. I also tried to find a transformation, but the
ones I selected found did not performed any better.
Thank you for your help,
Ricardo.
------------------------------------------------------------------------------
percent | Coef. Std. Err. z P>|z|
[95% Conf. Interval]
-------------+----------------------------------------------------------------
mm | -.8535189 .3593038 -2.38 0.018
-1.557741 -.1492963
_cons | 10.9801 .6719212 16.34 0.000
9.663157 12.29704
-------------+----------------------------------------------------------------
sigma_u | 5.1721451
sigma_e | 6.835591
rho | .36407729 (fraction of variance due
to u_i)
------------------------------------------------------------------------------
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
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