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Module 6: Line Graphs

This module provides information on arithmetic scale and semi-logarithmic or ratio scale line graphs.

Reviewed 15 April 05 /MODULE 6

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Secular Trends in never smoking among adolescent boys and girls aged 12 through 17 years: California, 1990-1999

55

60

65

70

75

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

Year

Pe

rce

nta

ge

Ne

ve

r S

mo

ke

rs

Female

Male

Arithmetic Scale Line Graph

Source: Am J Public Health, Dec.2003; 93:2101

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• Use: Show amount of change or difference in the dependent variable (vertical axis) for the different points of the independent variable (horizontal axis).

• For: Interval or ratio data.

Arithmetic Scale Line Graph

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Arithmetic Scale Line Graph

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Source: Am J Public Health, Dec. 2003;93:2089

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Source: Am J Public Health, Aug. 2000;90:1399

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Source: Am J Public Health, July 2001;91:1061

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Source: Am J Public Health, July 2000;90:1067

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• Use: Show rate of change in the dependent variable (vertical axis) for the different points of the independent variable (horizontal axis).

• For: Interval or ratio data.

Semi-logarithmic or Ratio Scale Line Graph

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Semi-logarithmic or Ratio Scale Line Graph

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0

20

40

60

80

100

120

1 2 3 4

Year

Ari

thm

eti

c S

cale

ABC

Arithmetic and Semi-log Scale Line Graphs

1

10

100

1 2 3 4

Year

Sem

i-Lo

g S

cale

ABC

Year A B C

1 10 60 12

2 20 70 24

3 30 80 48

4 40 90 96

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Semi-logarithmic Scale

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Ratio Scale

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Source: Am J Public Health, Mar. 2004;94:456

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Source: Am J Public Health, Mar. 1996;86:560

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A Line Graph and a Bar Chart with a Scale break