Chapter 2: Organizing Data

Section 1: Bar Graphs, Circle Graphs, and Time Plots

 Characteristics of Graphs

   Title       Horizontal scale labeled properly       Vertical scale labeled properly       Colors explained       Special symbols explained       Abbreviations explained       Data source

Avoids distortion, should not be misleading

Bar Graphs – are useful for quantitative or qualitative data. With qualitative data, the frequency or percentage occurrence can be displayed. With quantitative data, the measurement itself can be displayed.

Watch that the measurement scale is consistent or that a jump scale squiggle is

used.

Bar Graph

Grade Distribution

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10

A B C D F

Grades

Num

ber o

f Stu

dent

s

Circle Graphs - display how a total is dispersed into several categories. The circle graph is very appropriate for qualitative data, or any data where percentage of occurrence makes sense. Circle graphs are most effective when the number of segments are ten or fewer.  

Circle Chart

40%

20%

13%

10%

17%

Apple

Pumpkin

Peach

Cherry

Blueberry

Time Plot

Time Plots – display how data change over time. It is best if the units of time are consistent.

Miles Jogged in 30 min.

0

0.5

1

1.5

2

2.5

3

0 5 10 15 20 25

Week

Mile

s

Pareto Chart Pareto chart – is a

bar graph in which the bar height represents frequency of an event. In addition, the bars are arranged from left to right according to decreasing height.

Reasons for Tardiness

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10121416

Slept in Too longgettingdressed

Talking withparent too

long

Car Trouble Other

Reason

Num

ber o

f Tar

dies