The abscissa is a term used for coordinates on a line graph in opposition to the ordinate. The book uses the simplified meaning of the term, where abscissa refers to a given point’s coordinates on a graph’s x-axis.

A bar chart is a graph used to represent comparisons in the numbers of a given sample. Each bar represents a discreet category. The height of each bar—or length in the case of a horizontal bar chart—represents that category’s given value.

An index number is a number in statistics representing the change between two points. It is calculated by comparing the quantity of a thing with a base value. Index numbers such as price, which change over time, often appear in economics studies. Darrell Huff notes that they are often manipulated to suit political and commercial agendas.