I'm sorry, but Zelig does not support pairwise deletion. It does support however multiple imputation which is a standard approach of dealing with missing data. Kosuke --------------------------------------------------------- Kosuke Imai Office: Corwin Hall 041 Assistant Professor Phone: 609-258-6601 Department of Politics eFax: 973-556-1929 Princeton University Email: kimai(a)Princeton.Edu Princeton, NJ 08544-1012 http://imai.princeton.edu/ --------------------------------------------------------- On Thu, 27 Mar 2008, Keith Schnakenberg wrote: - Zelig Mailing List, served by Harvard-MIT Data Center Send messages: zelig(a)lists.gking.harvard.edu [un]subscribe Options: http://lists.gking.harvard.edu/?info=zelig Zelig program information: http://gking.harvard.edu/zelig/