Unit 2 (C):
Experimental
Research Designs
Mr. McCormick
A.P. Psychology
Do-Now
(Discussion)
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What is a correlation?
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What is a positive correlation?
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What is the correlation coefficient (r) for a
perfect positive correlation?
What does a positive correlation look like?
Provide an example of two things that may be
positively correlated.
What is a negative correlation?
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What is the correlation coefficient (r) for a
perfect negative correlation?
What does a negative correlation look like?
Provide an example of two things that may be
negatively correlated.
Non-Experimental
Research Designs
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Activity:
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With a partner, create an example of a psychological
phenomenon a psychologist would likely study for any 2 of the
following non-experimental research designs. Explain why.
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Naturalistic Observation
Case Study
Survey
Longitudinal Study
Cross-Sectional Study
Correlation
For each example, provide a short explanation of why each
research design would be most preferable for that scenario
Experimental Research Designs
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Experiment:
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A research method in which an investigator
manipulates one or more variables (independent variables)
to observe the effect on some behavior or mental
process (dependent variable)
Experimental Research Designs
 Why
might psychological researchers
prefer experimental research designs
over descriptive or correlational
research designs?
 What
type of research might require
an experimental design?
Experimental Research Designs
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Experiments begin with a hypothesis
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(e.g. “Caffeine improves test performance”)
Experimental Research Designs
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Experimenters must employ variables:
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Independent Variable:
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Dependent Variable:
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Manipulated/changed by experimenter to observe its
effects (e.g. Coffee/Redbull)
The effects/changes that occur in relation to the
independent variable (e.g. improved test performance)
Confounding Variables:
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Factors other than the independent variable that might
produce an effect in an experiment (e.g. one’s natural
intelligence)
Experimental Research Designs
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Experimenters divide participants into two
groups (often randomly):
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Experimental Group:
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Independent variable is applied (e.g. Coffee is given to
participants)
Control Group:
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Treated the same way as experimental group, but
independent variable is not applied (e.g. No coffee is
given to participants)
Experimental Research Designs
Why would experimenters
wish to employ an experimental
and a control group?
Experimental Research Designs
Does breast-feeding a child improve their intelligence later in life?
Review
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A psychologist wishes to test the effects of cell phone use on
driving. To do so, he creates an experiment in which 80
participants partake in a driving test. 40 participants must
talk on their phone while driving, while 40 participants may
not. Identify the following:
 Hypothesis
 Independent
Variable
 Dependent Variable
 Confounding Variables
 Experimental Group
 Control Group
Homework
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Unit 2 Quiz: “Research Methods”