#1

data(deere3)

arima(deere3, order=c(1,0,0),method='CSS') # AR(1) using least squares
arima(deere3, order=c(1,0,0),method='ML') # AR(1) using maximum likelihood

arima(deere3, order=c(2,0,0),method='CSS') # AR(2) using least squares
arima(deere3, order=c(2,0,0),method='ML') # AR(2) using maximum likelihood



#3

data(robot)

arima(robot, order=c(1,0,0),method='ML') # AR(1) using maximum likelihood
arima(robot, order=c(0,1,1),method='ML') # IMA(1,1) using maximum likelihood

AIC(arima(robot, order=c(1,0,0),method='ML') )
AIC(arima(robot, order=c(0,1,1),method='ML') )