charts present frequency distributions
graphically
Graphs and charts are commonly used ways
of presenting “pictures” of research results
Graphs and charts are very useful ways to
display the overall shape of a distribution

Sample Pie Chart: Religious
Identifications, 2008
Pie charts
are useful for discrete variables with only
a few categories.
The pie is divided into segments
which are proportional in size to the percentage of
cases in each category.

Sample Bar Chart: Religious
Identifications, 2008
Bar charts
are useful for discrete variables.
The
categories are represented by bars.
The height of
these bars corresponds to the number or percentage
of cases in each category.

Sample Bar Chart: Comparing Two
Variables

Histograms
Most appropriate for continuous interval-ratio
level variables, but can be used for discrete
interval-ratio level variables
Look like bar charts
Use real limits instead of stated limits
Categories (or scores) of the variable border
each other (the sides of the bars touch)

Constructing a Histogram from a
Frequency Distribution
1.
Array the real limits of the class intervals or
scores along the horizontal axis (abscissa)
2.
Array frequencies along the vertical axis
(ordinate)
3.
For each category, construct a bar with height
corresponding to number of cases and width
corresponding to real limits of class intervals
4.
Label each axis of graph
5.
Title the graph

Sample Histogram: Age, 2010

Line Charts
Sometimes called
frequency polygons
Constructed similarly to a histogram, except
graph a dot at each category’s midpoint and
then connect the dots
Especially appropriate for continuous
interval-ratio level variables
, but can be used
for discrete interval-ratio level variables

Sample Line Chart: Age, 2010

Line Charts: Marriage And
Divorce Rates Over Time
How would you describe the patterns?

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- Fall '19
- Bar chart, Joseph F. Healey, 46.58%