Measures of Central Tendency
Mean, Median, and Mode
If you were to pick one number that could best describe all the data in a set, what number would you pick? People usually pick a number somewhere in the middle of the data or a number that occurs most in the set.
There are three different ways to describe these measures of central tendency (also called average). Although the mean, median, and mode can be figured for almost any set of data, there are times when one of these measures is better than the others:
Mean: figure the mean (average) with sets of data that do not have very high or low numbers.
Median: figure the median with sets of data with a couple of numbers that are much higher or lower than most of the other numbers.
Mode: figure the mode with sets of data that have many identical numbers.
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Mean ~ The mean is the most common measure of average. It is found by adding all the numbers in a set and then dividing by how many numbers there are.
Example:
In the data set: 4, 5, 6
Step 1: add the numbers: 4 + 5 + 6 = 15
Step 2: divide by the number of addends (3), so 15 divided by 3 = 5
Answer: Mean = 5
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Median ~ is the number that fall exactly in the middle when you arrange the numbers in order from least to greatest.
Example:
In the data set: 6, 2, 9
Step 1: arrange in order from least to greatest: 2, 6, 9
Step 2: find the number exactly in the middle: 6
Answer: Median = 6
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Mode ~ this is the number that occurs most often in the set.
Example:
In the data set: 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 4
Answer: the mode is 2 because there are more 2's than any other number.
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