Next, fit AR(1) and AR(p) models to the CRSP returns:
arima(crsp,order=c(1,0,0))
arima(crsp,order=c(2,0,0))
(a) Would you prefer an AR(1) or an AR(2) model for this time series?
Explain your answer.
(b) Find a 95% confidence interval for ϕ for the AR(1) model.