1. Data Collection and Histograms
Unit 5: Statistics

2. Basic Statistics Data can be divided into 2 types:
Qualitative variable- places an individual into a group or category
ex: gender, college major, blue eyes, liberal
Quantitative variable- takes numerical data
ex: age, GPA, hours spent studying

3. Qualitative or Quantitative?
The height of each player on a basketball team?
The style of shoes worn by each student in a classroom?
The number of people in each household in the US?

4. Data Displays
The number of times a value occurs is known as the frequency of that value.
The relative frequency is the frequency divided by the total number of responses (written as a fraction, decimal, or %)
A frequency table displays the categories is frequencies, relative frequencies, or both.

5. Frequency Table Flavor Freq Relative Freq Vanilla Choc Butter Pecan
A group of people were asked their favorite flavor of ice cream. Of these, 6 chose vanilla, 12 chose chocolate, 4 chose butter pecan, and 8 chose mint chocolate chip. Create a table with frequencies and relative frequencies for each flavor.
Flavor
Freq
Relative Freq
Vanilla
Choc
Butter Pecan
Mint Choc

6. Let’s do our own…
Choose your favorite color from the table (only choose one). Let’s create a frequency table on the class’s findings.
Color
Freq
Relative Freq
Blue
Red
Yellow
Green

7. Displaying Data
Bar Graphs – displays the categories on the horizontal axis and the frequency or relative frequency on the vertical axis. The height of each bar shows the frequency of that value.

8. Displaying Data
Pie Charts – displays the categories and their relative frequencies.
All adds up to 100% - full circle!

9. Common Distribution Shapes
Uniform
Symmetric
Skewed Right
Skewed Left

10. The shape of data The last digit of each number in the phone book
The salaries of the employees of a corporation
The age of retirement for all people in the US
The heights of all adult women in the US

11. Stem Plots
Used to display data

12. Make a stem and leaf plot
32, 67, 89, 54, 98, 28, 59, 68, 75, 94, 49, 58, 100, 97, 76, 84, 82, 86, 94, 57, 67, 78

13. Histograms A bar graph with no gaps in between.
The frequencies are the heights of the bars.
The x-axis is divided into “classes” or intervals.

14. Make a histogram…
75, 65, 121, 100, 101, 89, 114, 63, 123, 127, 100, 96, 116, 109, 92, 131, 134, 105, 108, 117, 90, 89, 101, 101, 89, 98, 104, 130, 128, 97, 113, 129, 106, 87, 107, 68
Class
60-69
70-79
80-89
90-99
Freq

15. Homework
Exercises 13.1 Worksheet