Re: st: Re: Question about merging two datasets

[Ernest Berkhout <ernestb@seo.fee.uva.nl>]

At 00:03 1-9-2003, horowitz@fas.harvard.edu wrote:
> What if I have other variables besides city and income in dataset A and 
> dataset
> B (and they are different variables in each dataset) but I only want to merge
> in the matching incomes from dataset B to replace the incorrect ones in 
> dataset
> A (i.e. I want to leave alone the rest of the variables in dataset A)?
>
> Quoting Michael Blasnik <michael.blasnik@verizon.net>:
>
> > This appears to be a most basic merge.
> >
> > assuming that dataset A is already sorted by city, then:
> >
> > use B
> > sort city
> > merge city using A
> >
> >
> > These commands will result in a combined dataset where the value of income
> > from B takes precedence.
Please take a look at the magnificent mmerge.ado by Jeroen Weesie, it 
should handle your problem quite easily (type -ssc inst mmerge- ).
The trick is to specify that values of the master dataset A should be 
overwritten if there is disagreement with corresponding values in using 
dataset B. That is:

use A
mmerge city using B, ukeep(income) replace update



Ernest Berkhout
SEO Amsterdam Economics
University of Amsterdam

Room 3.08
Roetersstraat 29
1018 WB Amsterdam
The Netherlands

tel.:+ 31 20 525 1657
fax:+ 31 20 525 1686
http://www.seo.nl
===========================
A statistician: someone who insists
on being certain about uncertainty
===========================

*
*   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/