A Visual Display• A graph is a

visual display of information or data.

• This is a graph that shows a girl walking her dog.

1.3Communicating with Graphs

Take a closer look at this example graph and answer some questions about it:

1. What variable is labeled on the horizontal axis (at the bottom of the graph)?

FACT: We call the horizontal axis the x -axis.

2. What variable is labeled on the vertical axis (on the left)?

FACT: We call the vertical axis the y -axis.

3. Label the set of axes below as x or y:

A Visual Display

Communicating with Graphs

• The horizontal axis, or the x-axis, measures time.

• Time is the independentvariable because as it changes, it affects the measure of another variable.

1.3

A Visual Display

• The distance from home that the girl and the dog walk is the other variable.

• It is the dependent variable and is measured on the vertical axis, or y-axis.

Communicating with Graphs1.3

Examples of

If you want to know whether caffeine affects your appetite, the amount of caffeine would be the independent variable. How hungry you are would be the dependentvariable.

Youwanttocomparebrandsofpapertowelstoseewhichholdsthemostliquid.Theindependentvariableinyourexperimentwouldbethebrandofpapertowel.Thedependent variablewouldbetheamountofliquidabsorbedbyapapertowel.

A scientist studies how many days people can eat soup until they get sick.

The independent variable is the number of days of consuming soup. The dependent

variable is the onset of illness.

The dependent variable is how tall you are at different ages. The independent variable in this example would be _________________

You want to see how your height changes with age.

Now you try one!

What is the independent variable?What is the dependent variable?

A Visual Display

Communicating with Graphs

• Different kinds of graphs—line, bar, and circle—are appropriate for displaying different types of information.

3

A Visual Display• Graphs make it easier to understand complex

patterns by displaying data in a visual manner.

• Scientists often graph their data to detect patterns that would not have been evident in a table.

Communicating with Graphs

• The conclusions drawn from graphs must be based on accurate information and reasonable scales.

3

II. Types of GraphsLine Graph- A line graph

can show any relationship where the dependent variable changes due to a change in the independent variable.

3

Line Graphs Line graphs often show how a relationship between variables changes over time.

3

Constructing Line Graphs• The most important factor in making a line graph is

always using the x-axis for the independent variable.

Communicating with Graphs

• The y-axis always is used for the dependent variable.

3

Bar Graphs• A bar graph is useful for

comparing information collected by counting.

Communicating with Graphs3

For example, suppose you counted the number of students in every classroom in your school on a particular day and organized your data in a table.

Example of a Bar Graph

• You could show these data in a bar graph like the one shown.

3

Bar Graphs

• As on a line graph, the independent variable is plotted on the x-axis and the dependent variable is plotted on the y-axis.

3

Circle Graphs• A circle graph, or pie graph, is used to

show how some fixed quantity is broken down into parts.

Communicating with Graphs

• The circular pie represents the total.

• The slices represent the parts and usually are represented as percentages of the total.

3

Should our school require students to wear uniforms?

(student survey)

Music Preference for Young Adults

Section Check

A. listB. analysisC. visual displayD. conclusion

3Question 1

A graph is a(n) _______ of information or data.

Section Check3

AnswerThe answer is C. Graphs make complex patterns easier to understand by displaying data in a visual manner.

Section Check

Which of the following types of graphs wouldbe the best choice for representing a child’sgrowth over time?

A. lineB. barC. circleD. contour

3Question 2

Section Check3

AnswerThe answer is A. Line graphs often show how a relationship between variables changes over time.