11. Change Over Time
http://www.maps4kids.com/vizdata_pop.html
http://www.ted.com/talks/lang/en/hans_rosling_at_state.html
http://www.gapminder.org/ 11
13. Frequency Table
• A frequency table shows how a data set is
partitioned among all of several categories (or
classes) by listing all of the categories along
with the number of data values in each of the
categories.
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14. Simple Frequency Table
Statistical Reasoning, Bennett, et.al., 3rd edition
Cumulative Relative
Grade Frequency Grade Frequency
A 4=4 A 4 / 25 = 0.16
B 4 + 7 = 11 B 7 / 25 = 0.28
C 11 + 9 = 20 C 9 / 25 = 0.36
D 20 + 3 = 23 D 3 / 25 = 0.12
F 23 + 2 = 25 F 2 / 25 = 0.08
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15. Frequency Table Terms for
Quantitative Categories
• Lower class limits
• Upper class limits
• Class boundaries
• Class midpoints
• Class width
– No gaps between classes
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17. Constructing a Frequency Table
1. Determine number of classes
2. Calculate class width
3. Choose first lower class limit
4. List all lower class limits
5. List all upper class limits
6. Tally each data point next to appropriate
class limits
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21. Histogram
• A histogram is a graph of bars of equal width
drawn adjacent to each other (without gaps).
The horizontal scale represents classes of
quantitative data values. The vertical scale
represents frequencies.
• What characteristic of a data set can be better
understood by constructing a histogram?
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30. Pareto Chart
• When we want to attract attention to more
important data.
• Used for qualitative data, nominal not ordinal
– WHY?
• Bars arranged in descending order by
frequencies.
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37. “Bad” Graphs
• Graphics can offer clear and meaningful
summaries of statistical data.
However, even well-made graphics can be
misleading if we are not careful in
interpreting them, and poorly made graphics
are almost always misleading. Moreover, some
people use graphics in deliberately misleading
ways.
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