1. WHAT DO THEY ALL MEAN?

2. 4 ways to describe data The Mean – The average number in a data set. The Median – The middle number in a data set….. 50% of the numbers are above and 50% are below the median The Mode – The number that occurs most often. (Most popular) The Range – The difference between the maximum and minimum number.

3. MEASURE OF CENTRAL TENDANCY A number that helps describe where the middle of a group of data lies. The mean, median, and mode are measures of central tendancy.

4. This is what we usually mean when we say “What’s my average?” My MEAN old teacher calculates my AVERAGE! Mean

5. Finding The Mean Add all the numbers in the set together. Divide the sum by the number of data items in the set. The quotient is the mean of the set of numbers. My test grades are: 100, 88, 92 and 84 Add 100 + 88 + 92 + 84 = 364 Divide 364 by 4 –The mean is 91

6. Your grades on five tests: 95, 87, 92, 100, and 85 Put them in order from least to greatest 85, 87, 92, 95, 100 The middle number is the median Your median test grade is 92 – half the time you score below 92 and half the time below 92 Finding The Median

7. Your grades on six tests: 95, 87, 92, 100, and 94 Put them in order from least to greatest 85, 87, 92, 94, 95, 100 The middle is between 2 numbers The median is the mean of 92 and 94 Or 92 + 94 = 186 186 divided by 2 = 93

8. Finding The Mode The number in a data set that occurs most often Your grades: 95, 87, 85, 100, 100 Arrange the set of numbers from least to greatest 85, 87, 95, 100, 100 Your mode is 100

9. You don’t have to have a mode……. Some data sets have no mode or no number that occurs more than others Some might have two modes

10. Another way to describe data Asks the Question: How spread out is my data?

11. Finding The Range Back to your test scores: 100, 88, 92, and 84 Arrange the numbers in the set in order from least to greatest. 84, 88, 92, 100 Your maximum score is a 100 Your minimum score is 84 Your range is 100 – 84 = 16 The range = 16 or 84-100

12. It’s Time To Practice! Number of pets owned by 7 students: 2, 1, 1, 4, 3, 2, 1 What is the mean 2 What is the median2 What is the Mode 1 What is the Range 3