Stats Ch 1 and 2 vocab

Frequency table (Relative Frequency table)

lists the categories in a categorical variable and gives the count (or percentage) of observations for each category

Distribution

gives
1) The possible values of the variable, and
2) The relative frequency of each value

Area Principle

In a statistical display, each data value should be represented by the same amount of area

Bar chart (Relative Frequency Bar chart)

show a bar whose area represents the count (or percentage) of observations for each category of a categorical variable

Categorical data condition

The methods in this chapter are appropriate for displaying and describing categorical data. Be careful not to use them with quantitative data

Contingency table

displays counts and, sometimes, percentages of individuals falling into categories on two or more variables. The table categorizes the individuals on all variables at once to reveal possible patterns in one variable that may depend on the category of the other

Marginal distribution

In a contingency table, the distribution of either variable alone is called the ______________________________. The counts or percentages are the totals found in the margins (last row or column) of the table

Conditional distribution

A ____________________________________ restricts the WHO to consider only a smaller group of individuals

Independence

Variables are said to be independent if the conditional distribution of one variable is roughly the same for each category of the other

Association

When we see evidence that one variable depends on another, we say there's an association between them

Pie Chart

_________________ show how a "whole" divides into categories by showing a wedge of a circle whose area corresponds to the proportion in each category.

Context of Data

Who
What
Where
When
Why
How

Data table

An arrangement of data in which each row represents a case and each column represents a variable.

Cases

An individual (People, places, and things) whom or which we have data.

Variables (What, Columns)

Characteristics about each "who"

Population

All cases of interest

Sample

Smaller collection of cases of interest. The cases we actually examine in seeking yo understand the much larger population.

Data

Systematically recorded information, whether numbers or labels, together with its context.

Categorical variable

Names categories with words or numerals.

Quantitative variables

Recorded and used as numbers. These always have units.

Units

after the number that measures examples of these are: cm. in.