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					 AP Stat Day 8
   71 Days until AP Exam
        Displaying Categorical Data
            Bar Graphs, Pie Charts
Intro to Displaying Numerical Data
    Stem and Leaf Plots, Dot Plots
         Today’s Objectives
• Content Objective: I will be able to display
  categorical data in a bar graph and pie
  chart. I will be able to display numerical
  data in a dot plot and stem and leaf plot.
• Language Objective: I will work
  collaboratively to create each of the above
  graphs using class data.
                    Review
•   An individual is…
•   A variable is…
•   Categorical data is…
•   Quantitative data is…
•   All numerical data is quantitative- true or
    false?
                     Examples
Purchase    Name        Ship to        Price   Area Code
 Order
10675489   Katharine      Ohio         10.99     440

10783489   Samuel        Illinois      16.99     312

12837593     Chris     Massachusetts   15.98     413

15783947   Monique      Canada         11.99     902
         Distribution
• The pattern of
  variation that
  tells us what values the
  variable takes and how
  often it takes these values.
       Categorical Variables
• The values of a categorical variable are
  the categories’ labels (Ex: Male or
  Female)
• The distribution lists the categories and
  the count or percent of individuals
  that fall into that category.
              Making a Bar Graph

The x-axis labels are the categories



                                   The y-axis labels are counts or percents



         The bars DO NOT touch



                                   The graph needs a title as do the x- and
                                   y-axes.
                    Example
• To the right is             1st
                             Class
                                      2nd
                                     Class
                                              3rd
                                             Class
                                                     Crew   Total

  data from the
  Titanic. Make a
  bar chart from     Alive   203     118     178     212    711
  the data.

                     Dead    122     167     528     673    1490



                     Total   325     285     706     885    2201
  Beware the Shadowed Bars!
• While shadowed bars
  may look pretty, they
  can make a bar graph
  misleading.
• Also beware that the
  scale on the graph is
  clearly labeled and
  easy to read.
Making a Pie Chart

  You must           The pie
  include all        “slices” are
  categories that    the categories
  make up the
  whole data.


Your pie chart      The size of the
needs a key         pie slices
and a title         represents the
                    % the category
                    occupies
                  Example
• Using the Titanic               1st   2nd   3rd
                                 Class Class Class
                                                   Crew   Total

  data, make a pie
  chart of the dead by
  ticket type.           Alive   203   118   178   212    711



                         Dea     122   167   528   673    1490
                          d


                         Total   325   285   706   885    2201
             Activity Part 1
• Of the following, which is your favorite
  color?
Red
Blue
Green
Purple
Black
           Your turn

• Now, take the data we
  collected, and on pg. 6 of your
  journal create a bar
  graph and a pie chart.
    Displaying Numerical Data
• We will learn many ways to display
  numerical and quantitative data.
• One we used the other day in class- the
  dot plot.
• Today we will also learn about the stem
  and leaf plot (called stemplot for short)
          Making a Dot Plot


                                The y axis is not labeled, but dots
The x-axis is
                                 are stacked on common values
labeled with
                                giving height at certain x-values.
  numbers




            The dot plot needs a title, as does the x axis
                  Example
• To the right are       170   132
  winning times of the   158   162
  Kentucky Derby.
                         158   134
  Create a dot plot of
  this data.             160   160
                         159   159
                         133   155
                         158   158
                         163   161
                         158   133
                         160   166
         Making a Stem Plot
• A vertical line is drawn
• The left side of the line contains the
  “stems”
• The right side of the line contains the
  “leaves”
• The plot needs a key and a title.
                 Example
• Make a stem and leaf   88   56   72
  plot from the pulse    60   80   68
  data on the right.
                         72   80   84
                         64   72   80
                         76   64   76
                         84   76   72
                         76   64   80
                         64   68   68
           Splitting Stems
• Sometimes the distribution is unclear in a
  standard stem and leaf plot.
• One way to remedy this is to split the
  stems- meaning write the “stem” twice and
  have the “leaves” for 0-4 on one stem and
  5-9 on the second stem.
                    Example
• Using the pulse data,      88   56   72
  let’s practice splitting   60   80   68
  the stems.
                             72   80   84
                             64   72   80
                             76   64   76
                             84   76   72
                             76   64   80
                             64   68   68
   Distribution Characteristics
• Outlier- An individual observation
 that falls outside the overall
 pattern of the data
• Center- mean and median- they may not
  be the same…
• Spread- range
• Symmetry/ Shape
    Describing Distributions:
•C.u.s.s. and b.s
• Center
• Unusual Features
• Spread
• Symmetry
And
• Be Specific
            Activity Part 2
• How tall are you in inches?
• Record your height on the board.
• Write down the class data and use it to
  make a stemplot and a dotplot on the back
  of p. 6.
               Summary
What are key features of a bar graph?
   Of a pie chart?

What does CUSS & BS mean?
 do you understand how to do this?

WHEN do you make a bar graph or pie
 chart?
           Prep Questions
• What does frequency mean?

• Have you ever heard of a histogram?

• What do you think a time plot shows?

• What does cumulative mean?

				
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