Chapter 1

Individuals

The objects described by a set of data. Individuals may be people, animals, or things.

Variable

Any characteristic of an individual. A variable can take different values for different individuals

Categorical Variable

Places an individual into one of several groups or categories

Quantitative Variable

Takes numerical values for which it makes sense to find an average

Distribution

Distrubution of a variable tells us what values the variable takes and how often it takes these values

Marginal Distribution

One of the categorical variables in a two-way table of counts is the distribution of values of that variable among all individuals described by the table.

Conditional Distribution

A variable that describes the values of that variable among individuals who have a specific value of another variable. There is a separate conditional distribution for each value of the other variable.

Association

The value of one variable helps predict the value of the other.