[cem] "pair" function keeps running in R

Hi, I have a data set of 170K observations with 5 variables and want to match the treated and non-treated observations. So I used the following commands in R: mat <- cem(treatment = "treated", data = data, drop = todrop) psample <- pair(mat, data = data) The first command runs in couple of seconds. However, the second command runs for a day and then RStudio gets aborted and needs to be restarted. Any idea how to fix this? Many thanks, Meysam -- *Meysam Alizadeh* Postdoctoral Fellow | Center for Complex Networks and Systems Research School of Informatics and Computing Indiana University Bloomington Web <http://malizad.github.io> | Twitter <https://twitter.com/M_Aliizadeh> | LinkedIn <https://qa.linkedin.com/in/malizadeh>