# Statistics chapter 3

displaying and describing categorical data

## Terms

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- simpsons paradox
- when averages are taken across different groups, they can appear to contradict the overall averages.
- independence
- variables are said to be independent if the conditional distribution of one variable is the same for each category of the other
- conditional distribution
- the distribution of a variable restricting the WHO to consider only a smaller group of individuals is called a conditional distribution
- contingency table
- displays count and percentages of individuals falling into named categories on two or more variables. the tables categorizes the individuals on all variables at once, toreveal possible patterns in one variable that may be contingent on the category of the other
- pie chart
- pie charts show how a "whole" divides into categories by showing a wedge of a circle whose area corresponds to the proportion in each category
- distribution
- distribution of a variable gives: a. the possible values of the variable | relative frequency of each value
- marginal distribution
- in a contingency table, the distribution of either variable alone is called the marginal distribution. the counts or percentages are the totals found in the margins (last row or column) of the table
- area principal
- in a statistical display, each data value should be represented by the same amount of area
- frequency table
- lists the categories in a categorical variable and gives the count or percentage of observations fore each category
- bar chart
- show a bar representing the count of each category in a categorical variable