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04/21/23Marketing Research 1
Allow demonstration of causality
◦ A causes B
Relatively small sample sizes needed
◦ Minimum of 20 per experimental “cell”
04/21/23Marketing Research 2
CAUSE
◦ Independent variable
OUTCOME
◦ Dependent variable
04/21/23Marketing Research 3
CAUSE OUTCOME
1. Temporal ordering of variables
2. Evidence of association
(“concomitant covariation”)
3. Control of other causal factors
04/21/23Marketing Research 4
5
•Laboratory •Controlled setting.
•Field
•Natural environment, such as a store or mall
SettingSetting
6
Internal:
The extent to which competing explanations for
the findings observed can be ruled out.
External:
The extent to which the findings will apply to
outside persons, settings, and times.
ValidityValidity
Manipulate variable of interest◦ Independent variable: IV
◦ (Variable we can control)
Hold all else constant◦ Extraneous variables
Measure outcome◦ Dependent variable: DV
◦ (Variable we cannot directly control)
04/21/23Marketing Research 7
Researchers at Madigan Army Medical Center examined effectiveness of duct tape on warts.
The 51 patients between 3 and 22 were randomly assigned to receive either cryotherapy or duct tape. Patients in the cryotherapy group received a standard 10 second application of liquid nitrogen, repeated every two to three weeks. In the other group, a small piece of duct tape was placed on the patients' warts and patients were told to keep the tape on for six days. At the end of six days, they removed the tape, soaked the area in water, and used an emery board or pumice stone to rub the dead skin off.
Warts were successfully removed in 60 percent (15 of 25) of the patients in the cryotherapy group versus 85 percent (22 of 26) of the patients in the duct tape group. The duct tape group reported fewer side effects than cryotherapy group who reported pain and burning at the site.
Overall, the researchers found duct tape to be more effective, less painful, and less expensive than freezing.
04/21/23Marketing Research 8
Assignment to condition◦ Randomly assign subjects to condition OR◦ Match subjects on variable of interest
Manipulation◦ Experimental group gets it◦ Control group does not get it
Measurement of DV◦ Pretest◦ Posttest
04/21/23Marketing Research 9
Pretest posttest control group design:
◦ Experimental Group R O1 X O2
◦ Control Group R O3 O4
Posttest only control group design:
◦ Experimental Group R X O1
◦ Control Group R O2
04/21/23Marketing Research 10
Design that investigates the effect of two
or more independent variables on a
dependent variable
Allows testing of interactions and
contingent conditions
04/21/23Marketing Research 11
Men
Women
Ad A Ad B
65
65
70 60
Main Effectsof Gender
Main Effects of Ad
>
>
100
90
80
70
60
50
40
30
20
10
Ad A Ad B
Women
Men
Bel
ieva
bilit
y
Interaction Between Gender and Advertising Copy
Experimental research is the best way to
test causation.
Experimental research is inherently
reductionistic.
Complex designs allow the comparison of
several factors simultaneously, including
interactions.
04/21/23Marketing Research 14
04/21/23Marketing Research 15