not sure whether the regressions per se are the right thing to do, but its
seems reasonable. using cem to balance the 2 cross-sections is a creative
application of the technology.
Gary
--
*Gary King* - Albert J. Weatherhead III University Professor - Director,
IQSS - Harvard University
GKing.Harvard.edu <http://gking.harvard.edu/> - King(a)Harvard.edu -
@kinggary<http://twitter.com/kinggary>- 617-500-7570 - Asst 495-9271 -
Fax 812-8581
On Tue, Nov 2, 2010 at 8:10 PM, Reynaldo T. Rojo Mendoza <rtr11(a)pitt.edu>wrote;wrote:
Hello,
I am currently working on a paper where I use one-shot survey data from
2006 and 2008 (repeated cross-sections, exact same variables) and, although
they are supposed to be random samples drawn from the same population, there
is considerable multivariate imbalance on demographic variables. Thus, I
used CEM on the pooled sample (with year as “treatment”) to make the samples
comparable:
UNWEIGHTED MEANS
year education male age urban
2006 8.572 0.493 37.611 0.792
2008 8.269 0.495 40.841 0.692
Multivariate L1 distance: .34852375
CEM WEIGHED MEANS
year education male age urban
2006 8.204 0.492 40.278 0.700
2008 8.256 0.492 40.696 0.700
Multivariate L1 distance: 2.355e-15
My question is whether it makes sense to run *separate regressions* for
2006 and 2008 using the respective CEM weights obtained from the pooled
sample.
Hope you can help. Thanks!
Reynaldo T. Rojo Mendoza
Ph.D. Student
Department of Political Science
University of Pittsburgh