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