Visualizing Data

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Section 2-3

• Visualizing Data

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VISUALIZING DATA
In this section, we will learn various ways that
data can be visualized. The goal is not simply
to construct graphs and diagrams but rather to
learn something about the data and understand the
nature of their distributions.
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HISTOGRAMS
A histogram is a bar graph in which the
horizontal scale represents classes of data
values and the vertical scale represents
frequencies (or relative frequencies). The
heights of the bars correspond to the frequency
values, and the bars are drawn adjacent to each
other without gaps.
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QWERTY WORD RATING FREQUENCY HISTOGRAM
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QWERTY WORD RATING RELATIVE FREQUENCY HISTOGRAM
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HISTOGRAM AND RELATIVE FREQUENCY HISTOGRAM
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DRAWING A FREQUENCY HISTOGRAM ON THE TI-83/84

• Press STAT select 1Edit.
• Enter your data values in L1. (Note You could
  enter them in a different list.)
• Press WINDOW. Set Xmin to the lower class
  boundary of the first class set Xmax to the
  upper class boundary of the last class and set
  Xscl to the class width. (Note You may need to
  set Ymin and Ymax to see the histogram.)
• Press 2ND, Y (for STATPLOT). Select 1Plot1.
• Turn the plot ON. For Type, select the histogram
  (last one on first row).
• For Xlist, put L1 by pressing 2ND, 1.
• For Freq, enter the number 1.

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FREQUENCY POLYGON
A frequency polygon uses line segments connected
to points above class midpoint values.
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OGIVE
An ogive is a line graph that depicts cumulative
frequencies.
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DOTPLOT
A dotplot consists of a graph in which each data
value is plotted as a point (or dot) along a
scale of values. Dots representing equal values
are stacked.
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STEM-AND-LEAF PLOTS
A stem-and-leaf plot represents data by
separating each value into two parts the stem
(such as the left most digit) and the leaf (such
as the right most digit).
Stem
Leaves
Raw Data (Test Grades) 67 72 85 75
89 89 88 90 99 100
6 7 8 9 10
7 2 5 5 8 9 9 0 9 0
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PARETO CHARTS
A Pareto chart is a bar graph for qualitative
data, with the bars arranged in order according
to frequencies.
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EXAMPLE OF A PARETO CHART
Accidental Deaths by Type
Frequency
Fire
Falls
Poison
Firearms
Drowning
Motor Vehicle
Ingestion of food or object
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PIE CHART
Firearms (1400. 1.9)
Ingestion of food or object (2900. 3.9
Fire (4200. 5.6)
Motor vehicle (43,500. 57.8)
Drowning (4600. 6.1)
Poison (6400. 8.5)
Falls (12,200. 16.2)
Accidental Deaths by Type