2 Apr
2008
2 Apr
'08
10:59 a.m.
Thank you, Gary. I changed about 100 zeros to 0.1 and took the log. Now both the subgroup
and the
"other" distribution are right skewed. The subgroup looks a little better: the
bulk looks almost
normal but it has a VERY long left tail.
And I'm still concerned if imputations for the subgroup will be affected by the
higher scores in
the "other." Is setting mean and SE for the subgroup enough to take care of
that?
Qian
On Wed, 2 Apr 2008 10:37:35 -0400 (EDT)
Gary King <king(a)harvard.edu> wrote:
why don't you try taking the log before imputation.
Gary
On Wed, 2 Apr 2008, Qian Guo wrote:
> Hi Amelia folks,
>
> I have a question about imputing for highly skewed distributions. My data
> have missing test scores for 540 out of 709 observations in a lower-achieving
> subgroup and no missing scores for the other students (about 129,000 in
> size). The problem is that the subgroup has a highly left skewed distribution
> while the overall distribution is highly right skewed.
>
> I set priors by giving the mean (16.07 out of 40, versus 31.68 for the other
> students) and standard deviation (9.30 vs. 7.20) of the subgroup. But would
> it still be a problem that the subgroup distribution is highly left skewed
> (and so unlike the rest of the population)? Thanks a lot.
>
> All very best,
> Qian Guo
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