Adapted from Ms. Namad

Terminology Individuals- the objects described by a set of data. They may be people, animals, or things. Variable: any characteristic of an individual. It can take different values for different individuals. There are two types of variables: categorical and quantitative

Categorical Data Two-Way Tables: describes two categorical variables Marginal Distribution: one of the categorical variables in a two-way table of counts is the distribution of values of that variable among all individuals described by the table Ex: (a+c)/(n)

Categorical Data Conditional Distribution: variable describes the values of that variable among individuals who have a specific value of another variable Ex: c/(c+d)

Does the distribution have one or more peaks (modes) or is it unimodal? Is the distribution approximately symmetric or is it skewed in one direction? Is it skewed to the right (right tail longer) or left?

Shape Left- Skewed Right- Skewed

Example Description Shape: The distribution is roughly symmetric with a single peak in the center. Center: You can see from the histogram that the midpoint is not far from 110. The actual data shows that the midpoint is 114. Spread: The spread is from 80 to about 150. There are no outliers or other strong deviations from the symmetric, unimodal pattern.