I want to use linear mixed effect model for a set of data.
After using lme4 package and
lmer() function and fitting model, I want to validate my model for other period time. But I don't know how to validate my model and generate predicted values.
Do you have any ideas about useful validation method? Is there any command about validation in R software?
Thanks for your useful comments.
I fitted model to one set of data and now I want to check its performance for an other data set. I want to plot figure by "predicted value" and "observed value" and calculate R^2 to evaluate model performance.