Glossary

Matrix

An atomic vector that has two additional attributes: a number of rows and a number of columns.

Data Frame

A two-dimensional data structure in R in which the columns are atomic vectors that can be of different types.

Case (also called an Individual)

An individual unit under study. In a data frame in R, the rows correspond to cases.

Variable (in Data Analysis)

In data analysis, a variable is a measurement made on the individuals in a study.

Categorical Variable (in Data Analysis)

In data analysis, a categorical variable is a variable whose values cannot be expressed meaningfully by numbers.