#Read in data
oil.price <- read.table("https://edoras.sdsu.edu/~babailey/stat673/oil.price.dat", header=TRUE)

#oil.price <- read.table("/Users/bbailey/Desktop/Teaching/ST673/oil.price.dat", header=TRUE)

oil <- ts(oil.price)

par(mfrow=c(2,2))
plot(oil, main="Oil")

plot(log(oil), main="Log Oil")

plot(diff(oil), main="Diff Oil")

plot(diff(log(oil)), main="Diff Log Oil")

par(mfrow=c(3,2))
acf(oil,main='Sample ACF of the Oil Price TS')
acf(log(oil), main="ACF of log Oil")

acf(diff(oil), main="ACF of Diff Oil")
acf(diff(log(oil)), main="ACF of Diff Log Oil") 

pacf(diff(oil), main="PACF of Diff Oil")
pacf(diff(log(oil)), main="PACF of Diff Log Oil") 

#Models: ARIMA(2,1,0) or ARIMA(0,1,1)