Re:st: Preventing double counting

[Christopher Baum <kit.baum@bc.edu>]

<>
On Dec 8, 2011, at 2:33 AM, Michael wrote:

> I have state-to-state migration data that is as follows:
> 
> orig_state	dest_state	netmigration
> 1		1		0	
> 2		1		25
> 3		1		.
> 1		2		-25
> 2		2		0
> 3		2		44
> 1		3		.
> 2		3		-44
> 3		3		0
> 
> 
> There is an origin state, a destination state, and net migration between the two. I don't want to double count net migration so I only want to keep a single observation for each state pair. Does anyone have any suggestions about how I could get rid of the second observation that gives me the negative net migration of the first observation?

to produce the 'lower triangle' (actually, subdiagonal) of the flows matrix,

keep if orig_state < dest_state

Kit

Kit Baum   |   Boston College Economics & DIW Berlin   |   http://ideas.repec.org/e/pba1.html
                             An Introduction to Stata Programming  |   http://www.stata-press.com/books/isp.html
  An Introduction to Modern Econometrics Using Stata  |   http://www.stata-press.com/books/imeus.html


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