Graphs/Charts for Qualitative Variables

(Always label all axis/categories etc, include a title, and give units if necessary.)

A description of the distribution of a qualitative variable gives the categories and the number/% of individuals in those categories.
Two common graphical methods of displaying the distribution of a qualitative variable are:
Pie Charts - Give the categories and show the % of individuals in those categories as a fraction of the circle - as in the diagram below.


Bar Graphs - Show each of the categories as a bar, and represent the number or % of individuals in each category using the height of the bar - as in the diagram below.

Statistical Terms

Data Set - Information about a group of individuals (e.g. a group of students.)

Individual - An object described in a data set (e.g. a student.)

Variable - Any characteristic of an individual (e.g. a students height or gender.) Variables can take different values for different individuals.

Categorical/Qualitative Variable - Describes a category that an individual falls into (e.g. race, gender, eye color etc.)

Quantitative Variable - A numerical value that describes a characteristic of an individual (e.g. height, weight etc.)

Distribution of a Variable - The values a variable takes in a data set and how often it takes those values.

Observation - A value we see taken by a variable for a particular individual.

Outlier - An observation much higher or lower than the majority of observations in a data set.
e.g. in the data set
1, 7, 2, 3, 4, 3, 4, 5, 6, 2, 3, 856, 3, 4
856 is an outlier.