APEX AP Stats 3.6 Overview Cateogrical Bivariate Data: Two-Way Tables Study Guide

Categorical Variable

A variable containing categorical data.

Conditional Distribution

The number of observations in a cell expressed as a proportion, or percentage, of the marginal frequency of the row or column. When conditional distributions are named, the first name is the denominator.

Formula for the conditional distribution

part/whole

Contingency Table

Another term for a two-way table.

Joint Frequencies

The number of observations for each row and column in a two-way table.

Marginal Distribution

A distribution that indicates the proportion or relative frequency of the total observations that fall into each level of either the row or column variable.

Marginal Frequencies

The number of observations for each row and column in a two-way table. The set of row frequencies or column frequencies should sum to the total sample size.

Row and Column Percents

The row (or column) percentages indicate the percentages of the total observations that fall into each row (or column) variable.

Simpson's Paradox

The fact that aggregating proportions can reverse the direction of the relationship seen in the individual pieces.

Table Cells (In a Two-Way Table)

Cells represent combinations of the levels of the row and column variables in a two-way table. The values in table cells are typically counts, frequencies, or percentages.

Two-Way Table

A table designed to present and summarize information about two categorical variables. The table consists of rows that reflect levels of one variable and columns that reflect levels of a second variable. Each combination of row and column is considered a cell. Two-way tables are often used to examine the relationship between two different variables.