Page 162 - Math Course 1 (Book 2)

Misleading Graphs

Mo. 11

Lesson 4 Price of Lemons Graph B

1.60
1.40
KEY CONCEPTS: 1.20
1. Recognize when graphs are misleading. 1.00
2. Evaluate predictions and conclusions Dollars per pound 0.80
based on data analysis. 0.60
0.40
0.20
MO. 11 - L4a 0.00
‘98 ‘00 ‘02 ‘04
Year
Recognize Misleading Graphs FOOD
The graphs show the decrease in the price of
lemons. Why do the graphs look different?
Compare the two Graphs

Answer The horizontal scales differ.

85 100
84 80 The graphs show the decrease in the price of
83 60 lemons. Which graph appears to show a more rapid
decrease in the price of lemons after 2002? Explain.
82 40
81 20
Graph B; the slope of the line
2007 2008 2007 2008 Answer from 2002 to 2004 is steeper
in Graph B.
Days of Freezing Temps Days of Freezing Temps

Both show exactly the same data. However, the Accuracy of Predictions and Conclusions
graph on the left makes the change appear to be
much larger than it really is because the number on
the vertical axis do not start 0. Each vertical mark Example
on the left graph represents I and each mark on the
right represents 20(the scale changes.)
INTERNET
The graph shows the percent of Internet use in
Let’s Begin different age groups. According to the graph, more
18- to 24-year-olds are using the Internet than the
other age groups. Determine whether this state-
ment is accurate. Justify your reasoning.
Real World Example Internet User(%)
60
Price of Lemons Graph A 50
1.60 percent 40 58.7 53.3 53.8 54.8
1.40 20 35.1 10.7
Dollars per pound 1.00 0 18–24 25–34 35–44 45–54 55–64 65–up
1.20
Age
0.80
0.60
No, the statement is not accurate.
Even though the 18-24 age group
0.40
0.20 Answer has the greatest percent of users,
0.00 the other age groups span a
‘98 ‘99 ‘00 ‘01 ‘02 ‘03 ‘ 04 greater age range and thus have
more people.
Year
154