conducting experiments © 2012 the mcgraw-hill companies, inc

CONDUCTING EXPERIMENTS

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Distinguish between straightforward and staged manipulations of an independent variable

Describe the three types of dependent variables Self-report Behavioral physiological

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Discuss sensitivity of a dependent variable, contrasting floor effects and ceiling effects

Describe ways to control participant expectations and experimenter expectations

List the reasons for conducting pilot studies Describe the advantages of including a

manipulation check in an experiment

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Samples May Be Drawn From the Population Using: Probability sampling Nonprobability sampling Sampling must assure external validity to

generalize to other populations Determine the Sample Size

Larger samples provide more accurate estimates of population values

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Setting the Stage Types of Manipulations

Straightforward manipulations Staged manipulations

Use of a confederate or accomplice

Strength of Manipulation Does the study maintain external validity?

Cost of the Manipulation

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Types of Measures Self-report measures Behavioral measures Physiological measures

Galvanic skin response (GSR) Electromyogram (EMG) Electroencephalogram (EEG) Functional MRI (fMRI)

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MEASURING

THE DEPENDENT VARIABLE

Sensitivity of the Dependent Variable Ceiling effect Floor effect

Multiple Dependent Measures Cost Measures Ethics

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MEASURING THE DEPENDENT VARIABLE

Controlling for Participant Expectations Demand characteristics

Using unrelated filler items on a questionnaire Placebo groups

Can control through the use of placebo effect Used to assure external validity is maintained

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Controlling for Experimenter Expectations Experimenter bias or expectancy effects Research on expectancy effects Solutions to the expectancy problem

Single-blind experiment Double-blind experiment

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Research Proposals Pilot Studies Manipulation Checks Debriefing

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Statistical Analysis of the Data Examine and Interpret the Pattern of Results Decide whether there really is a relationship

between the independent and dependent variables

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Journal Articles Peer Review As many as 90% of papers submitted to the more

prestigious journals are rejected Professional Meetings

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