Name: ______________________________________________________ Period: ___________

Using Graphing Skills

Graphs are used to show numerical information in a useful format. Graphs help us understand and interpret data. They can be powerful tools for examining cycles and trends. The three main types of graphs are circle graphs, line graphs and bar graphs.

Circle Graphs:

A circle graph, sometimes called a pie chart, shows different parts of the data in relation to all of the data. Each part of the circle represents a different part of the data and the entire circle represents all of the data. For example, a biology studying a plot of land in a hardwood forest in Wisconsin found that there were five different types of trees in the plot. The data table below summarizes the biologistís findings.

Wisconsin Hardwood Trees

Type of Tree

Number Found

Percentage of total

(rounded to the nearest whole %)

Oak

539

17

Maple

758

24

Beech

319

10

Birch

1327

42

Hickory

222

7

Total

3165

100

 

Figure 1:

Line Graphs:

While circle graphs are useful for depicting percentages, line graphs are most often used to demonstrate continuous change between two variables. A line graph has one or more lines connecting a series of points. Along the horizontal or x-axis you will find the most consistent variable which is the manipulated (independent) variable. Along the vertical axis or y-axis you will find the responding (dependent) variable. Examine the following data.

Time

Distance from the Rangerís Station (miles)

7 a.m.

0

8 a.m.

4

9 a.m.

6

10 a.m.

8

11 a.m.

10

12 p.m.

12

1 p.m.

12

2 p.m.

10

3 p.m.

10

4 p.m.

10

 

Figure 2:

Title: The Effect of Time on the Distance from the Rangerís Station in miles

http://vickimartinez.com/line_graph_2.png

 

 

 

Bar Graphs:

Sometimes it is not appropriate to use a pie chart or line graph to represent data. Consider the following information:

Date

Precipitation (cm)

Date

Precipitation (cm)

April 1

0.5

April 9

.025

April 2

1.25

April 10

0.0

April 3

0.0

April 11

1.0

April 4

0.0

April 12

0.0

April 5

0.0

April 13

0.25

April 6

0.0

April 14

0.0

April 7

0.0

April 15

6.50

April 8

1.75

 

 

 

It would be impossible to plot the data as represented on a pie chart. Days on which there was no precipitation could not be shown. It is also inappropriate to use a line graph to represent the data for precipitation. Consider, for example, the period from April 13 to April 15. If the points between April 13 and April 15 were connected, the graph would indicate that over 3 cm of precipitation fell on April 14. However, April 14 was a sunny day and no precipitation fell on that day. A bar graph is appropriate for data that are not continuous. Sometimes the x-axis has labels rather than a numerical scale. This type of bar graph is used to show comparisons.

Figure 3:

Title: The Effect of Dates in April on the Precipitation in centimeters

 

 

Construct your own line graph:

1.      When plotting data on a line graph, you must decide which variable is the manipulated (independent) variable and label the x-axis. Donít forget to include the units used. The responding (dependent) variable is placed along the y-axis. Label the y axis and donít forget to include the units used.

2.      Then you must decide on the scale of each axis, that is, how much each line along the axis represents. Scales should be chosen to make the graph as large as possible within the limits of the graph paper and still include the largest item of data. Scale units should also be selected for ease of locating points on the graph. Multiples of 1, 2, 5 or 10 are the easiest to work with.

3.      Next you must title your graph. Follow the formula ďThe Effect of  __X__ on __Y__Ē with X = the label on the x-axis and Y= the label on the y-axis.

4.      Plot the points in two different colors for the different sets of data and draw a best fit line for each set of colored points. Make a key or legend.

Time After Eating (hours)

Glucose level of Person A

(mL/L of blood)

Glucose level of Person B

(mL/L of blood)

0.5

170

180

1.0

155

195

1.5

140

230

2.0

135

243

2.5

140

235

3.0

135

225

4.0

130

200

 

 

 

 

 

 

 

 

 

 

 

TITLE: ______________________________________________________________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Construct your own bar graph:

1.      When making a bar graph, you must decide which variable is the manipulated (independent) variable and label the x-axis. Donít forget to include the units used. The responding (dependent) variable is placed along the y-axis. Label the y axis and donít forget to include the units used.

2.      Then you must label the bars (the spaces between the lines) on the x-axis.

3.      Then you must decide on the scale for the y-axis, that is, how much each line along the y-axis represents. Scales should be chosen to make the graph as large as possible within the limits of the graph paper and still include the largest item of data. Scale units should also be selected for ease of locating points on the graph. Multiples of 1, 2, 5 or 10 are the easiest to work with.

4.      Next you must title your graph. Follow the formula ďThe Effect of  __X__ on __Y__Ē with X = the label on the x-axis and Y= the label on the y-axis.

5.      Draw bars in two different colors to represent the two set of data. Make a key or legend.

Month

Average Precipitation for Fairbanks, Alaska (mm)

Average Precipitation for

Belem, Brazil (mm)

January

38.1

300.0

February

27.9

295.5

March

30.5

290.1

April

35.6

282.7

May

45.7

146.3

June

63.5

140.2

July

81.3

123.3

August

88.9

100.7

September

58.4

85.6

October

63.5

54.6

November

50.8

105.3

December

48.3

296.4

 

 

 

 

 

 

 

 

TITLE: ______________________________________________________________________