Thank you so much for your assistance (and your
patience). With -fillin-, setting duration=0 when
_fillin=1, and then -reshape-, I got exactly what I
needed. Whew!
Melonie
--- n j cox <[email protected]> wrote:
> This response y has not so far appeared in the
> drama.
> Where does it come from? The same dataset?
>
> Either way, I think you might make progress by
> checking out -reshape-.
>
> Melonie Sullivan
>
> Okay, so far so good, thanks. But now how do I get
> that information into a matrix of this form - one
> line
> for each youth:
>
> youthid y x1 x2 x3 x4 x5 x6
> 11 0 15 41 0 0 . 0
> 12 1 0 13 0 42 0 55
>
> where y=dependent variable, x1=duration if group=1,
> x2=duration if group=2, etc. If I take your
> solution,
> then generate x1, x2...., and do a -list- I still
> get
> a 6x6 matrix of x for each youth that looks like
> this:
>
> youthid x1 x2 x3 x4 x5 x6
> 11 15 . . . . .
> 11 . 41 . . . .
> 11 . . . . . .
> 11 . . . . . .
> 11 . . . . . .
> 11 . . . . . .
>
> < intermediate posts>
>
> > >> I have data on history of placements into
> > different
> > >> -group-s by -youthid-: there are multiple
> > placement
> > >> records for each youth. I need to create a
> > variable
> > >> equal to the sum of -duration- of all
> placements
> > into
> > >> each -group- for each youth. -collapse (sum)-
> > seems to be
> > >> the appropriate procedure, but it treats
> missing
> > >> values as zeroes. This causes a problem if a
> > youth has
> > >> only one placement in a given group with
> unknown
> > >> duration. Example:
> > >>
> > >>
> > >> youthid group duration
> > >> 11 1 15
> > >> 11 1 .
> > >> 11 2 31
> > >> 11 2 10
> > >> 11 5 .
> > >> 12 2 5
> > >> 12 2 8
> > >> 12 4 42
> > >> 12 6 55
> > >>
> > >> I create a duration variable for each group
> > (-generate
> > >> grp1dur = duration if group==1-, etc.) and
> > -collapse
> > >> (sum)- by -youthid- and I want to get this:
> > >>
> > >> youthid 11 12
> > >> grp1dur 15 0
> > >> grp2dur 41 13
> > >> grp3ddur 0 0
> > >> grp4dur 0 42
> > >> grp5dur . 0
> > >> grp6dur 0 55
> > >>
> > >> But collapse gives me a zero on grp5dur for
> youth
> > #11,
> > >> though youth #11 had placement in that group,
> > albeit
> > >> of an unknown duration. The other zeroes are
> > correct;
> > >> the youth had zero days in that placement
> group.
> > >>
> > >> The problem has been addressed here before,
> best
> > in
> > >> the following post by Nick Cox:
> > >>
> > >>
> >
>
http://www.stata.com/statalist/archive/2004-07/msg00783.html
> > >>
> > >> However, this is not solving my particular
> > problem,
> > >> because my data essentially looks like a big
> > stack of
> > >> Nick's "toy datasets" -- one for each of 1800
> > youth in
> > >> my data. So collapsing by (youthid) gives the
> > same
> > >> value of Nick's allmissing for each youth,
> since
> > the
> > >> allmissing tags missing durations for groups
> > within
> > >> youths.
>
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