This chapter will make use of two datasets that come pre-installed with Incanter: the Longley dataset, which contains data on seven economic variables measured in the United States between the years 1947 to 1962, and the Airline dataset, which contains the monthly total airline passengers from January 1949 to December 1960.

The Airline dataset is where we will spend most of our time in this chapter, but first let's look at the Longley dataset. It contains columns including the gross domestic product (GDP), the number of employed and unemployed people, the population, and the size of the armed forces. It's a classic dataset for analyzing multicollinearity since many of the predictors are themselves correlated. This won't affect the analysis we're performing since we'll only be using one of the predictors at a time.