1. Measures of Central Tendency
Mean, Median, and Mode

2. Numbers called measures of central tendency can be used to describe the center of data. The most common of these is mean, median, and mode.

3. Mean
The mean of a set of data is the sum of the data divided by the number of items in the data set.
Also referred to as the average.

4. Mean example
Data set: 4, 1, 5, 2, 2, 4, 2, 4
First add all the numbers together:
= 24
Then divide by the number of items in the set
24 ÷ 8 = 4
Mean = 4

5. Median
The median of a set of data is the middle number of the data when ordered from least to greatest.
If two numbers are in the middle, find the mean (average) of those two numbers.

6. Median Example 1 Data set: 15, 17, 12, 19, 11
First order from least to greatest:
11, 12, 15, 17, 19
Then find the number in the middle
Median = 15

7. Median Example 2 Data set: 15, 11, 7, 20, 20, 17
First order least to greatest:
7, 11, 15, 17, 20, 20
Two numbers are in the middle - 15 and 17
Find the mean (average) of the two
= 32 ÷ 2 = 16
Median = 16

8. Mode
The mode (or modes) of a set of data is the number or numbers that occur the most often.

9. Mode Example EXAMPLE 1: Data set: 50, 45, 45, 52, 49, 56, 42
Mode = 45 (occurs the most often)
EXAMPLE 2:
Data set: 29, 34, 27, 29, 34, 19, 38
Modes = 29 and 34