1. Types of Variables
AP Statistics
06-07
Dobson

2. Review of Terms
Individual: The objects described by a set of data, individuals may be people, animals or things
Ex: Students in an AP Statistics class
Variable: any characteristic of an individual. A variable can take on different values for different individuals
Ex: Heights of individuals: Student #1: 5’ 5” Student #2: 5’ 7” Student #3: 5’ 2”

3. Two Types of Variables Quantitative:
Numeric value that it makes sense to do arithmetic operations (+, -, x, /)
Finding an arithmetic “average” makes sense
EX:
Height
Weight
Age
Income
Test Scores

4. Types of Variables Categorical
Records which of several groups or categories to which an individual belongs
If there are only 2 possible categories, the variable is called binary
Ex:
Gender
Race
SES (socio-economic status)
Marital status

5. Caution!!!
Most quantitative variables can be asked in such a way as to make them a categorical variable.
Ex: Age:
Please choose the category that describes how old you are
OVER 80

6. Determine if the variable is Quantitative or Categorical
Height
Armspan
Whether or not the individual went to sleep before 12:00am
Month of birth
Distance from home
Whether the individual has a cell phone
How many messages a person has sent in the last 24 hours
The age of a bride on her wedding day
Whether the bride is older, younger, or the same age as the groom in a wedding couple
The number of letters in a person’s last name
Check your answers on the next slide

7. Quantitative Variables
Height
Armspan
Distance from home
How many messages a person has sent in the last 24 hours
The age of a bride on her wedding day
The number of letters in a person’s last name
Categorical
Whether or not the individual went to sleep before 12:00am
Month of birth
Whether the individual has a cell phone
Whether the bride is older, younger, or the same age as the groom in a wedding couple

8. Further Resources Practice of Statistics: pg 4-7 Homework Assignment:
1-1: Problem #1a-p :