Transcript Bar graphs, Pie charts, Dot plots, and Stem plots

Bar graphs, Pie
charts, Dot plots and
stem plots
AP Statistics
What is an Individual?
Individual: Individuals are the objects
described by a set of data. Individuals
may be people, but they may also be
animals or things.
 What are some examples of individuals?
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BAR GRAPHS
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Step 1: Label your axes of the graph. Draw a set of
axes. Label you horizontal axis with your type that your
categories fit in to. Title your graph.
Step 2: Scale your axes. Use the counts in each
category to help you scale your vertical axis. Write the
category names at equally spaced intervals beneath the
horizontal axis.
Step 3: Draw a vertical bar above each category name
to a height that corresponds to the count in each
category.
PIE CHARTS
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QUICK NOTE: When given Categorical Data in counts.
Find the total of the counts and use each count divided
by the total to find the percent. Then place the
categories in a circle as pie slices according to their
percent. Make a legend to color code the pie chart per
category.
Example 1.2 p.8 : The following table displays the sales
figures and market share (percent of total sales) achieved
by several major soft drink companies in 1999. That year,
a total of 9930 million cases of soft drink were sold.
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Company
Cases Sold (millions)
Coca Cola Company 4377.5
Pepsi-Cola Company 3119.5
Dr. Pepper/7-up
1455.1
Cott Corp.
310.0
National Beverage
205.0
Royal Crown
115.4
Other
347.5
Market share
44.1
31.4
14.7
3.1
2.1
1.2
3.4
Analyzing categorical Data
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The best way to analyze Categorical Data is from a
graph. Lets Analyze the graph from Example 1.3 p. 10
Group Work
Quantitative Variables
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A quantitative variable takes numerical
values for which arithmetic operations
such as adding and averaging make
sense
DOT PLOTS
Step 1: Label your axis and title your
graph. Draw a horizontal line and label it
with the variable. Title your graph
 Step 2: Scale the axis based on the
values of the variable
 Step 3:Mark a dot above the number on
the horizontal axis corresponding to each
data value.
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Example 14 page 11: The number of goals scored by each
team in the first round of the California Southern Section
Division V high school soccer playoffs is shown in the
following table.
5
0
3
0
3
0
1
0
1
0
2
0
7
0
1
2
3
0
1
1
2
0
5
0
4
0
3
SHAPES
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Skewed Right: Most of the data is concentrated
to the left of the graph (tail point to the right)
Skewed Left Most of the data is concentrated to
the right of the graph (tail points to the left)
Symmetric: The majority of the data is
concentrated in the center of the graph (shaped
like a bell)
What is the shape of the dot plot?
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YES, It is skewed right.
Center and Spread
Center: the value that divides the
observations so that about half have
smaller values
 Spread: the smallest and larges values
expressed in an interval
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What are the center and spread of
the dot plot?
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The center is 1 and the spread is 0 through 7
Stemplots
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Step 1: Separate each observation into a stem
consisting of all but the rightmost digit and a leaf, the
final digit
Step 2: Write the stems vertically in increasing order
from the top to bottom and draw a vertical line to the
right of the stems. Go through the data, writing each leaf
to the right of its stem and spacing the leaves equally.
Step 3: write the stems again, and rearrange the leaves
in increasing order out from the stem.
Step 4:_ title your graph and add a key describing what
the stems and leaves represent.
Example 1.5 Watch that Caffeine
Construct a Stem Plot with the
data.