Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

Re: st: bug: non-unique merge


From   khigbee@stata.com
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: bug: non-unique merge
Date   Wed, 05 Oct 2005 08:42:54 -0500

James Muller <james.muller@reventlov.com> said:

> I have noticed a little problem with non-unique merging, when the sort
> option is used. Sort appears to set the 'unique master' option. I'll
> give an example:
>
> <cut>
>
> The error I receive is that "variable id does not uniquely identify
> observations in the master data". If re-run the above example except
> manually sort each dataset and do not set the sort option then it
> returns a warning rather than an error.
> 
> The help on merge describes the 'unique' option as options as, if
> specified then uniqueness is a requirement but otherwise it is not. I
> quote:
>
> <cut>
> 
> There is nothing said in the description of the sort option. And so
> the above example should produce the dataset:
>
> <cut>
>
> It isn't anything serious, I know, but it's not the stated behaviour
> for merge.

Look at the options table under the syntax diagram in -help
merge- (or in the manual for [D] merge).  At the bottom of that
table it says

    sort implies unique.

So it is not a bug.  But, it looks like we should state this
again down in the options section.  I will see about changing
merge.hlp (and eventually the manual) so that in the description
of the -sort- option down in the Options section it will also say
this.

Ken Higbee    khigbee@stata.com
StataCorp     1-800-STATAPC

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index