I've attached the data to this message. http://r.789695.n4.nabble.com/file/n4641291/2005pip.csv 2005pip.csv -- View this message in context: http://r.789695.n4.nabble.com/mgcv-package-problems-with-NAs-in-gam-tp4641253p4641291.html Sent from the R help mailing list archive at Nabble.com.