Experiments!
There’s only one game in this
town!
Experiments
Only research method that allows us to
draw conclusions about cause-and-
effect relationships.
Chances of isolating the variable causing
a particular effect are much greater.
Hypothesis
First step in an experiment: design a
hypothesis-educated guess
Reflects cause-and-effect relationship.
Variables allows hypothesis to be
measured more accurately.
Independent/Dependent Variables
Hypothesis should include two variables.
Independent Variable (IV): causes
something to happen. Ex. What causes the
behavior to happen.
Dependent Variable (DV): should show the
effect of the IV. Ex. The behavior that
researchers are looking for. (ALWAYS
measured)
Groups
Experiments have 2 types of groups
Experimental group- participants in an
experiment that are tested (exposed to the
IV)
Control group- participants in an experiment
not exposed to the IV. (gets the placebo)
Double-Blind Procedure
Assigning participants to the experimental
and control groups by chance.
Equally distributes individual differences.
Not even the experimenter knows what
group they’re in.
Confounding Variable
A 3rd variable that could influence the DV.
Researchers must control for
confounding variables.
If not, the experiment cannot show cause-
and-effect relationships between IV and
DV.
Random assignments critical!!
Control for Confounding Variables
Make sure participants are aware of
hypothesis
Double-blind procedure-another
safeguard against confounding variables
Placebo-used in some experiments (drug
studies), non-active substance.
Data Analysis
Run the experiment and collect the data
Analyze numbers-find out if hypothesis
was supported
Replication
Repeating a study to see if results can be
reproduced (IMPORTANT)
Safeguard required in an experiment.
Only once-no cause-and-effect
relationship between IV and DV.
Ex. ESP (real or not?)
REVIEW!
Hypothesis
Identify DV and IV
Randomly select participants
Randomly assign to experimental and control
groups
Expose experimental group to IV
Control confounding variables (double-blind)
Learn impact of IV by measuring DV
Statistical analysis