[gov2001] General interest instrumental variables question

Hi everyone, Here is a question about instrumental variables. It might be useful for everyone. Say you get lucky and come up with a bunch of valid instruments. When running your IV regressions, should you use the instruments separately, or should you throw them all in one regression? I am not sure which approach is more theoretically justifiable. I've seen the first reported in economics papers frequently, but the Zelig option where you can stick in a bunch of instruments at once calls out at me. Best, Erin _______________________________________________ gov2001-l mailing list gov2001-l(a)lists.fas.harvard.edu http://lists.fas.harvard.edu/mailman/listinfo/gov2001-l -- gov2001 mailing list served by Harvard-MIT Data Center List Address: gov2001(a)lists.gking.harvard.edu Subscribe/Unsubscribe: http://lists.gking.harvard.edu/?info=gov2001