GraphingSection 1.3

Why use graphs? Graph- used to make data easier to read

and understand- shows patterns and trends

What is a graph? Visual display of information or data X-axis- horizontal- independent variable Y-axis- vertical- dependent variable Must have labels for each axis, a title, and

units if appropriate You must select the proper scale.

Don’t make the scale too large or too small Make sure you can read the data easily

Examples of Proper Scale and Improper ScaleDistance Traveled in One Day

0

50

100

150

200

250

300

350

400

450

1 2 3 4 5 6 7 8 9 10 11

Time (hours)

Dist

ance

(mile

s)

Distance Traveled in One Day

-60

40

140

240

340

440

540

640

740

-5 0 5 10 15 20 25

Time (hours)

Dis

tanc

e (m

iles)

0

50

100

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450

1 2 3 4 5 6 7 8 9 10

Time

Types of Graphs Line, Bar, Pie Line Graph

Shows relationship between dependent and independent variable- often shows change over time

Can compare more than one event as long as scale is the same

Used most often in this class and science in general

Reading Line Graphs

Reading Line Graphs Linear Relationships- makes a straight line

both sets of numbers increase both sets of numbers decrease one set increases while the other set decreases one set of numbers increases while the other

stays exactly the same one set of numbers decreases while the other

stays exactly the same.

Plant Growth

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5

Week

Heig

ht (in

ches

) Series1

Linear (Series1)

Height of Grass vs. Fertilizer

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1

2

3

4

5

6

7

0 2 4 6 8 10

Fertilizer (oz)

Heig

ht (in

ches

)

Series1

Linear (Series1)

Temperature of Creek at various Depths

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5

10

15

20

25

30

0 5 10 15 20 25

Depth (cm)

Tem

pera

ture

(Cels

ius)

Series1

Linear (Series1)

Reading Graphs Interpolation- reading between data points Extrapolation- reading beyond data points

Less reliable than Interpolation Maybe something unexpected occurs after known

data points

Temperature in Room after Turning on Heat

15

17

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25

27

0 5 10 15 20 25 30

Time (minutes)

Tem

pera

ture

(deg

rees

Cel

sius

)

A

b

c

Problems with graphs You might use the wrong scale

Don’t put two different units on the same graph- like Celsius and Fahrenheit or Celsius and Kelvin

Can be used to distort data- maybe the scale is manipulated to make something seem worse than it is or not as bad as it is

Temperature in Room after Turning on Heat

15

65

115

165

215

265

315

0 5 10 15 20 25 30

Time (minutes)

Tem

pera

ture

(deg

rees

Cel

sius

)

A

b

c

Bar Graph + Circle/ Pie Bar: Compare information collected by

counting Example: Comparison of how many in this class

like which cookies. Try it.

Circle/Pie: Shows how something can be broken down into parts Shows percents

Making Circle/Pie Graphs Use our cookie data:

Determine % of each category Multiply % by 360

Gives you degrees of the circle Make Graph- will need protractor and compass