1. Displaying Distributions with Graphs
Section 1.1

2. There are two ways to display categorical variables
Bar Graphs
Pie Charts

3. How to Construct a Bar Graph
Label your axes and title your graph
Scale your axes
Draw a vertical bar above each category name—make sure bars are at equally spaced intervals

4. Displaying Quantitative Variables
Dotplots
Label your axes and title your graph
Scale your axes
Mark a dot above the number on the horizontal axis corresponding to each data value

5. Displaying Quantitative Variables
Stemplots
Separate each data observation into a stem (all but the right most number) and leaf (final number)
Write stems vertically in increasing order and draw a vertical line to the right of the stems
Write the leaves in increasing order to the right of their corresponding stem
Title your graph and add a key

6. Displaying Quantitative Variables
Histograms
Divide the range of the data into classes of equal width— make sure there is no overlap of your classes
Count the number of observations that fall into each class
Label and scale your axes and title your graph
Draw a bar that represents the count in each class—there is no space between bars

7. When examining quantitative variables, you want to look for key components
Shape
Center
Spread
Outliers

8. Shape Three types of shape
Symmetric—left and right sides of the graph are approximate mirror images of each other
Skewed to the right—right side extends out farther than the left
Skewed to the left—left side extends out farther than the right

9. Symmetric

10. Skewed to the Right

11. Skewed to the Left

12. Practice Problems pg. 10 #1.5, 1.6 pg. 16 #1.8 pg. 18 #1.11

13. Percentile
The pth percentile of a distribution is the value such that p percent of the observations fall at or below it
For example, if you are said to be in the 65th percentile for height in your age group then you are as tall or taller than 65% of people your age

14. Ogive Also known as a relative cumulative frequency graph
Helps to find information of an individual observation

15. How to Construct an Ogive
Make a frequency table like you do for a histogram
Add three more columns: relative frequency, cumulative frequency, and relative cumulative frequency
Label and scale your axes and title your graph
Plot a point corresponding to the relative cumulative frequency at the left of the next class interval
Begin line at 0% and connect the dots

16. Time Plot
Plots each observation against the time at which it was measured
Time is always on the horizontal axis
Dots may or may not be connected

17. Practice Problems
pg. 34 #1.24, 1.25, 1.27, 1.28, 1.29