Unit 2 Section 2.2

2.2: More Graphs and Displays  Several types of graphs are used in statistics besides histograms, frequency polygons, and ogives.  Other graphs include:  Stem and Leaf  Dot Plots  Pie Graphs  Pareto Charts  Scatter Plots  Time-Series Graphs

Stem and Leaf Plot  Stem and Leaf Plot – data plot that uses part of the data values as the stem and part of the data values as the leaf to form groups or classes.  Tips for Drawing Stem and Leaf Plot  Arrange the data in order.  The trailing digit becomes the “leaf,” while the first digit(s) becomes the “stem.”  i.e. for the number 14, 1 is the stem and 4 is the leaf.  i.e. for the number 115, 11 is the stem and 5 is the leaf.  Data is grouped in order based on values that share the same stem. Section 2.2

Example 1: Stem and Leaf Plot  Create a Stem and Leaf plot using the following info: Number of Cardiograms Performed Over 20 Days Section

Dot Plot  Dot Plot – each data entry is plotted using a dot on a number line.  Tips for Drawing Dot Plot  Make sure your number line contains the lowest and highest data value.  Pick a scale that is easy to use  Plot each data value above the corresponding number on the number line.  If a value is represented two or more times, plot additional dots above the previous. Section 2.2

Example 2: Dot Plot  Create a Dot plot using the following info: Number of Cardiograms Performed Over 20 Days Section

Pie Graph  Pie Graph – a circle that is divided into sections or wedges according to the percentage of frequencies in each category of the distribution.  Tips for Drawing Pie Graphs  Determine the degree measure for each piece of the pie.  Take the frequency, divide it by the sum of the frequencies, then multiply it by 360 degrees.  Determine the percentage for each piece of the pie.  Create the graph Section 2.2

Example 3: Pie Graph  Create a Pie Graph using the following info: Pounds of Snacks Eaten During the Super Bowl Section 2.2 SnackPounds (Frequency) Potato Chips11.2 million Tortilla Chips8.2 million Pretzels4.3 million Popcorn3.8 million Peanuts2.5 million

Pareto Charts  Pareto Chart – used to represent a frequency (or relative frequency) distribution for a categorical variable.  Frequencies are displayed as the height  Bars are arranged from the highest to the lowest.  Tips for Drawing Pareto Charts  Make the bars the same width.  Arrange the data from largest to smallest according to frequency.  Make the units that are used for the frequency are equal in size. Section 2.2

Example 4: Pareto Chart  Create a Pareto Chart using the following info: Average Cost Per Mile for Passenger Vehicles on State Turnpikes Section 2.2 StateNumber Indiana2.9 cents Oklahoma4.3 cents Florida6.0 cents Maine3.8 cents Pennsylvania5.8 cents

Homework  Pg. 62 (5 – 11 ODD, 17, 23, 25, 27)  Read and take notes on Section 2.2 (pgs ) Section 2.2