I see what you are getting at.
-father- is irrelevant to the -merge-. You
can merge on -id- without problems with this
example.
Nick
[email protected]
louis boakye-yiadom
> Perhaps an example will clarify my concern. Suppose we have
> the following
> datasets, where -id- (the identifier) represents family code:
> Dataset1
> id father
> 1. 1 John
> 2. 2 Peter
> 3. 3 Sam
>
> Dataset2
> id child
> 1. 1 Bill
> 2. 2 Joe
> 3. 2 Mary
> 4. 3 Phil
> 5. 3 Sue
> 6. 3 Pat
>
> I was thinking that even though -id- does not uniquely identify each
> observation in dataset 2, the datasets can still be merged
> using -id- as the
> match variable to obtain a result like the following:
>
> id father child
> 1. 1 John Bill
> 2. 2 Peter Joe
> 3. 2 Peter Mary
> 4. 3 Sam Phil
> 5. 3 Sam Sue
> 6. 3 Sam Pat
>
> Or is it that this kind of merge is not called match merge? Thanks.
"Nick Cox" <[email protected]>
> >Let's turn this round. If this is not true,
> >how do you expect match merge to work?
louis boakye-yiadom
> > > Is it true that "for a match merge to work, the identifier or
> > > identifiers
> > > must uniquely identify each observation"? I found this
> > > statement in sample
> > > lecture NC 101 (one of StataCorp's NetCourses), but I thought
> > > that this
> > > requirement (of the id uniquely identifying each observation)
> > > is often
> > > desirable, but not necessary in all cases. Any insights will
> > > be appreciated.
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