title: Response to letter.
authors.affiliation: FHI 360, 359 Blackwell Street, Suite 200, Durham, NC 27701, USA. Electronic address: dhubacher@fhi360.org.
authors.forename: David
authors.initials: D
authors.lastname: Hubacher
authors.affiliation: Office of Population Research, Wallace Hall, Princeton University, Princeton, NJ 08544-1005, USA; University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: James
authors.initials: J
authors.lastname: Trussell