No doubt this is what is often
wanted. But the help for -uvis-
is explicit:
Note that uvis will not impute observations for which
a value of a variable in xvarlist is
missing. Only complete cases within xvarlist are used.
Nick
n.j.cox@durham.ac.uk
Richard Williams
> At 10:03 PM 2/24/2005 +0000, you wrote:
> >You seem surprised at this.
> >
> >If you don't know -x1-, you cannot
> >predict -y- from -x1 x2 x3-; and
> >so on.
> >
> >If you do know -y- you don't need
> >to impute it.
>
> If I understand Quang correctly, then the latter is exactly
> the point.
> -uvis- should have just plugged in the observed value for y
> rather than
> even try to impute it; but instead, it plugged in a missing
> value since one
> or more of the Xs for that case was missing.
>
> I tried -uvis- on a data set where y was not missing but some
> values of x
> were. The generated y had missing data whereas the original
> y did not.
>
> I'm not that familiar with the programs but if nothing else
> one work around
> might be
>
> replace uvis_y = max(original_y, uvis_y)
>
> where uvis_y is the var generated by uvis. If I've done this
> correctly,
> then whenever -uvis- generated an unnecessary MD code for y,
> the original
> non-missing value for y will get plugged back in.
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