Interpreting Communication Research Chapter 2 Laboratory Experimental Research

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Interpreting Communication ResearchChapter
2Laboratory Experimental Research

• By
• Frey, Botan, Friedman, Kreps

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Experimental ResearchOverview
Experiments compare groups of people
Experiments attempt to discover causal principles
Experiments investigate whether one variable
causes another variable to change
Changes in the dependent variable must be shown
to be the result of changes in the independent
variable and not due to some other variable(s)
The researcher must rule out competing
explanations for changes in the dependent
variable (extraneous or confounding variables)
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Types of Experiments

• Full (true) Experiments
• maximum amount of control
• Laboratory Experiments
• take place in a setting created by the researcher
• Field Experiments
• take place in a natural environment
• Quasi-Experiments
• moderate control
• Pre-Experiments
• little or no control

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Factorial Experiments
Experiments that study the effects of two or more
independent variables are called factorial
experiments
Factorial experiments tell us 2 things
(1) the effects of each independent variable
(called main effects), and
(2) the effects of the independent variables
working together (called an interaction effect)
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EXERCISING A HIGH DEGREE OF CONTROL
(1) MANIPULATING AN INDEPENDENT VARIABLE
(2) RANDOMLY ASSIGNING SUBJECTS TO EXPERIMENTAL
CONDITIONS
(3) ACCOUNTING FOR THE INFLUENCE OF EXTRANEOUS
VARIABLES
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Questions for Examining Full Experimental
Research Lets look at pages 30-32

• Are the hypotheses clearly stated?
• Was the manipulation of the independent variables
  successful?
• How well did the researcher do in controlling for
  extraneous variables?

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Anticipated Interaction and Information Seeking
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Review of Douglas study, Anticipated
Interaction and Information Seeking
Well break up into small groups (say, 3 people
per group) and each group will summarize Douglas
study. Write down the summary. And each group
will present their summary to the whole class.
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GO