Monthly US retail gasoline price (the average price per gallon, in dollars) and the spot price of a barrel of West Texas Intermediate (WTI) oil in dollars as traded at Cushing, Oklahoma. Jan 1991 - Nov 2006.



bivariate time series


Hyndman, R.J., Koehler, A.B., Ord, J.K., and Snyder, R.D., (2008) Forecasting with exponential smoothing: the state space approach, Springer.

References These series are available from the US Energy Information Administration website


par(mar=c(5,4,2,5)) plot(gasprice[,1], xlab="Year", ylab="Average retail price per gallon (dollars)", main="Gasoline and oil prices")
par(new=TRUE) plot(gasprice[,2], col="blue", xaxt="n", yaxt="n", xlab="", ylab="")
mtext("Spot price per barrel (dollars)", side=4, line=3)
legend("topleft", col=c("black","blue"), lty=1, legend=c("Ave retail price of gasoline", "Spot price of WTI oil"))