Variables

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# Variables - PowerPoint PPT Presentation

Variables. Members: Fine 083-2 Mill 108-2 Pooppup 189-6. What is Variable?. A variable is any factor, trait or condition that you are testing in the experiment. It can be varied or changed according to the experimenter . There are many types of variables existed. Independent variable.

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## PowerPoint Slideshow about 'Variables' - tessa

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### Variables

Members:

Fine 083-2

Mill 108-2

Pooppup 189-6

What is Variable?
• A variable is any factor, trait or condition that you are testing in the experiment. It can be varied or changed according to the experimenter.
• There are many types of variables existed.

A variable that leads, influences or predicts the outcome of the study.

It lies at the heart of any experimental design.

EXAMPLE

You are interested in how stress affects heart rate in humans.

independent variable : the stress

dependent variable : the heart rate.

You can directly manipulate stress levels in your human subjects and measure how those stress levels change heart rate.

A WORD OF CAUTION

In identifying independent variables students often get confused with distinguishing between the independent variable and the levels of the independent variable.

You may understand that there are three independent variables, when there is only one independent variable with three levels

LEVELS OF INDEPENDENT VARIABLES

A teacher is doing a study of Instructional Methods.

One class was taught only with lecture and no visuals

Another class was taught using the book and worksheets

A third class was taught only using PowerPoint

In this example there is only one independent variable – Instructional Methods; but there are three levels of that variable.

Dependent Variable
• A dependent variable is what you measure in the experiment and what is affected during the experiment.
• It is called dependent because it "depends" on the independent variable.
• In a scientific experiment, you cannot have a dependent variable without an independent variable
Example: Dependent Variable
• For example, if we want to measure therate of growth of the plants.
• Therefore, the rate of growth of the plants is the dependent variable.(the thing that we are measuring)
• Therefore, we can see that the Independent Variable is water for the plants.
• Thedependentvariable isthe rate of plant growth.

Mr. Wuu is driving at a constant rate of 65 miles per hour on the expressway. The function d=65h represents the no. of miles d he has traveled after h hours. Which quantity is the dependent variable, independent variable? Which is neither?

1.Miles traveled

2.Speed

3.65 miles

4.Hours traveled

Extraneous variable

Undesired (add error to the experiment)

May influence the relation between the dependent and in dependent variable

Often research studies do not find evidence to support the hypotheses because of unnoticed extraneous variables that influenced the results.

Extraneous variable (Cont.)

A major goal in research design is to decrease or control the influence of extraneous variables as much as possible.

If, however, a variable cannot be controlled for, it becomes what is known as a confounding variable.

Types of Extraneous Variable

Participant Variables

-related to individual characteristics of each subject that may impact how the subject responds

-example: background differences, mood, anxiety, intelligence

2. Situational Variables

-relate to the environment that may impact the individual subject

- example: taking a test in a chilly room, the temperature would be considered an extraneous variable

Example

A researcher is doing research on the effectiveness of a computer mathematic lesson on long division compared to a typical mathematic lesson by measuring with the same standard test. The sample group the researcher choose was a class of fourth grade students form SatitKhonKaen. The researcher divided the class randomly into two equal groups. The first group used the computer lesson and the second group learnt with a typical lecturer for the exact same amount of time. Then took the exact same standard test.

The sample group the researcher choose was a class of fourth grade students form SatitKhonKaen.

The researcher divided the class randomly into two equal groups.

-The first group used the computer lesson

-The second group learnt with a typical lecturer for the exact same amount of time.

Then took the exact same standard test.

Example(cont.)

Independent variable: the fourth grade class form SatitKhonKaen, the number of students in each group, the time of learning, the standard test, lesson on long division

Dependent variable: The score on the standard test

Extraneous Variable: Gender, age, each student’s background, mood, anxiety, intelligence, the enviornment of the room used for testing

Reference