Categorical Data (2) Flashcards
Frequency Table
This is a way to list the categories in a categorical variable and give the count of observations for each category.
Relative Frequency Table
Lists the categories in a categorical variable and gives the percentage of observations for each category.
Area Principle
In a statistical display, each data value should be represented by the same amount of area.
Bar Chart
A type of chart that shows a bar whose area represents the count of observations for each category of a categorical variable.
Relative Frequency Bar Chart
Area of each bar represents the percentage of observations for each category of a categorical variable.
Pie Chart
A type of chart that shows how a “whole” divides into categories by showing a wedge of a circle whose area corresponds to the proportion in each category.
Categorical data condition
Before making a bar chart or pie chart, always check that the data are counts or percentages of individuals in a categories.
Contingency Table
A way to display counts of individuals falling into categories on two or more variables to reveal possible patterns in one variable that may be contingent on the category of the other.
Marginal Distribution
In a contingency table, the distribution of either variable alone are the totals found in the margins (last row or last column) of the table.
Conditional Distribution restricts…
… restricts the Who of a variable to consider only a smaller group of individuals.
Independence
Variables are this if the conditional distribution of one variable is the same for each category of the other.
Segmented Bar Chart
This type of chart displays the conditional distribution of a categorical variable within each category of another variable.
Simpson’s Paradox
When averages are taken across different groups, they can appear to contradict the over-all averages. (e.g. UC Berkeley admissions study)
