1. 3.2 Day II: Measures of Central Tendency
By the end of class you will be able to calculate the frequency table mean and weighted mean, and all measures of central tendency by using a calculator.

2. Frequency Table Mean
Used when the given data are presented in a frequency table.
Must use class midpoints instead of actual raw data.

3. Presidential Inauguration Age

4. Presidential Inauguration Age
Modal Class

5. Weighted Mean Mean computed by assigning data different weights
w = weight, x = data value
First test: 85, counts for 20% of grade
Second test: 90, counts for 30% of grade
Third test: 75, counts for 50% of grade

6. Journal Reflection
Write down anything you think you need to remember to calculate a frequency table mean or weighted mean.

7. Central Tendency & Calculator
For mean & median enter the raw data in L1
In the Stat menu calculate 1-variable statistics
Do not round until the final answer
Round to one more decimal place than the original data

8. Frequency Table Mean & Calculator
Enter Class midpoints in L1
Enter Frequencies in L2
In Stat menu calculate 1 var statistics (L1,L2)

9. Weighted Mean & Calculator
Enter data values in L1
Enter weights in L2
In stat menu calculate 1 vars statistics (L1, L2)

10. Find the mean, median mode and midrange (age of thieves in a jail)

11. Find the Frequency Table Mean and Modal Class

12. Find the Weighted Mean (GPA)
Math: 3 credits A (4points)
English: 3 credits B (3 points)
Biology: 4 credits B (3 points)
Gym: 2 credits C (2 points)

13. Measures of central tendency and distribution shape
The shape of the distribution affects the location of the mean, median and mode

14. Symmetric Distribution
Data values are evenly distributed on both sides of the mean
When the distribution is unimodal, the mean, median and mode are the same and located at the center.

15. Right Skewed Order of central tendencies: mode, median, mean
Majority of data located to left of mean

16. Left Skewed Order of central tendency: mean, median, mode
Majority of data values to the right of the mean