Unit 1Section 1-5

1-5: Observational and Experimental Studies

Observational Study - the researcher merely observes what is happening or what has happened in the past and tries to draw conclusions based on these observations.

For Example: Motorcycle owners are getting older and richer.

Data was compared based on income of motorcycle owners over a period of time.

Section 1-5

Experimental Study – the researcher manipulates one of the variables and tries to determine how the manipulation influences other variables.

For Example: Sit-up motivation experiment

Quasi-Experimental Study – when random assignment is not possible, researchers use intact groups. The treatment should be assigned at random.

In either case, the group being manipulated is called the treatment group. The other is called the control group.

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Variables in Studies – usually include one or more independent variables and one dependent variable.

Independent Variable is the one being manipulated by the researcher. It can also be called the explanatory variable.

Dependent Variable is the one that you would like to determine whether it is being affected by the independent variable. It can also be called the outcome variable.

Observational Study Advantages:

Usually occurs in a natural setting (not a lab). They can be used when it is unethical or

dangerous to conduct an experiment. They also can be used when the researcher cannot

manipulate the variables.

Disadvantages: Definite cause and effect cannot always be

determined because other factors may have led to the results.

They can be expensive and time-consuming. They also can have unreliable data when relying

on recordings from the past.

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Experimental Study Advantages:

Researcher has much more control (over who is in groups and manipulating the independent variable).

Disadvantages: They may occur in unnatural settings such

as labs and special classrooms. This can lead to the Hawthorne effect They can also have confounding variables.

Section 1-5

Section 1-5

The Hawthorne Effect This effect was discovered in 1924 in a study of

workers at the Hawthorne plant of the Western Electric Company.

Subjects who knew they were participating in an experiment actually changed their behavior. Therefore, the results of the research was affected.

Confounding variables - one that influences the dependent variable but cannot be separated from the independent variable.

Complete pg. 16 #’s 1 – 6

Read and take notes on Section 1-6 (pg. 16-19)

Homework