I am running multiple GAMs using the step.gam function and am receiving an error. I have copied my code and bolded the error at the bottom. Any help is greatly appreciated. trout.gam2<-gam(cpue~s(lat,7)+as.factor(gear)+as.factor(bottom)+s(depth,7)+s(do,7)+s(sal,7)+s(temp,7),family=quasipoisson,data=trout) trout.gam3<-step.gam(trout.gam2,scope=list(+ "lat"=~1+lat+s(lat,3)+s(lat,7), "gear"=~1+as.factor(gear),"bottom"=~1+as.factor(bottom), "depth"=~1+depth+s(depth,3)+s(depth,7), "do"=~1+do+s(do,3)+s(do,7), "sal"=~1+sal+s(sal,3)+s(sal,7), "temp"=~1+temp+s(temp,3)+s(temp,7))) Start: cpue ~ s(lat, 7) + as.factor(gear) + as.factor(bottom) + s(depth, 7) + s(do, 7) + s(sal, 7) + s(temp, 7); AIC= NA Error in while (bAIC < AIC & steps > 0) { : missing value where TRUE/FALSE needed ____________________________________________ Luke McEachron Assistant Research Scientist Florida Fish and Wildlife Research Institute 100 8th Ave SE St. Petersburg, FL 33701 (727) 896-8626 x. 3046 ____________________________________________ [[alternative HTML version deleted]]