For the usgdp series: a. if necessary, nd a suitable Box-Cox transformation for the data; b. t a suitable ARIMA model to the transformed data using auto.arima() ; c. try some other plausible models by...

For the usgdp series:

a. if necessary, nd a suitable Box-Cox transformation for the data;

b. t a suitable ARIMA model to the transformed data using auto.arima() ;

c. try some other plausible models by experimenting with the orders chosen;

d. choose what you think is the best model and check the residual diagnostics;

e. produce forecasts of your tted model. Do the forecasts look reasonable?

f. compare the results with what you would obtain using ets() (with no transformation).