I am using a gam for a model predictor and need to forecast into the future based off data collected earlier. I would like to predict fish weight on day 10 from measures taken on a fish from day 2. This seems simple, but using predict, I have only been able to predict weight for a given day. A simple linear model may work as an example. I would like to know what the forecasted weight is of a fish on day 10, if the fish measured on day 2 was 30. Days<-1:10 Weight<-c(12,24,30,45,51,62,73,80,98,103) plot(Weight~Days) model<-lm(Weight~Days) pred<-predict(model,Days=2) I will then hopefully use the logic and apply it to my gam model predictions. Thanks, Keith M. Keith Cox, Ph.D. Principal MKConsulting 17105 Glacier Hwy Juneau, AK 99801 U.S. 907.957.4606 [[alternative HTML version deleted]]