Thank you so much that was very helpful. I actually have 4 years but the following code appears to do what I want it to (I think defining the variable as a factor was the key component I was missing):
- Code: Select all
multigroup.ddl$Phi$year=0
multigroup.ddl$Phi$year[multigroup.ddl$Phi$time==12.152]=1
multigroup.ddl$Phi$year[multigroup.ddl$Phi$time==11.23]=1
multigroup.ddl$Phi$year[multigroup.ddl$Phi$time==22.019]=2
multigroup.ddl$Phi$year[multigroup.ddl$Phi$time==22.982]=2
multigroup.ddl$Phi$year[multigroup.ddl$Phi$time==33.319]=3
multigroup.ddl$Phi$year=factor(multigroup.ddl$Phi$year)
Cheers,
Amanda