1. STA 2023 Section 2.2 Notes: More Graphs and Displays

2. Stem and Leaf Plot  Numbers are split into two parts.  The Leaf is the rightmost digit.  These must be single digits.  The Stem is the rest of the digits.  Example: 15|6 = 156.  Advantages  The graph still contains the original data values  Provides an easy way to sort data.

3. Example 1:Make a stem-and-leaf plot for this data. What can you conclude about the data?  The numbers of home runs that Barry Bonds hit in the first 18 years of his major league baseball career are listed below.  We input the data into a list in the calculator and put the list in ascending order. 162524193325344637 334240373449734645

4. Answer: Most of his years, he hit between 33 and 49 home runs.

5. Dot Plot  Each data entry is plotted, using a point, above a horizontal axis.  We can see the distribution of the data  Determine individual data points  Identify unusual data values.

6. Example 2: Construct a dot plot from the data.  The Highway Patrol, using radar, checked the speeds (in mph) of 30 passing motorists at a checkpoint. The results are listed below.  Answer: 4438415036 43424948 35403741435045 3938 50414736354042434833

7. Pie Chart  A circular chart that is divided into sections whose arc is proportional to the frequency.  Example 3: A study was conducted to determine how people get jobs. Four hundred subjects were randomly selected and the results are listed below.

8.  Find Relative Frequencies  Find the angles SourceFrequencyRelative Frequency Angle Newspaper want ads6917%62 Online Services12431%112 Executive search firms7218%65 Mailings328%29 Networking10326%93

9. Pareto Chart  A vertical bar graph that arranges items from greatest to smallest frequency.  Example 4: Create a Pareto Chart from the data from example 3.  Answer:

10. Scatterplot  This graph plots paired data sets to see any trends with the data.  Example 5: The data below represent the numbers of absences and the final grades of 15 randomly selected students from a statistics class. Use a scatter plot to display the data. Is there a relationship between the students' absences and their final grades?

12.  Answer:  In general, there appears to be a relationship between the absences and the final grades. As the number of absences increased, the students' final grades decreased.