05/03/23Marketing Research 1

Allow demonstration of causality

◦ A causes B

Relatively small sample sizes needed

◦ Minimum of 20 per experimental “cell”

05/03/23Marketing Research 2

CAUSE◦ Independent variable

OUTCOME◦ Dependent variable

05/03/23Marketing Research 3

CAUSE OUTCOME

1. Temporal ordering of variables

2. Evidence of association (“concomitant)

3. Control of other causal factors

05/03/23Marketing Research 4

5

•Laboratory •Controlled setting.

•Field

•Natural environment, such as a store or mall

SettingSetting

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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)

05/03/23Marketing 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.

05/03/23Marketing 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

05/03/23Marketing 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

05/03/23Marketing Research 10

Design that investigates the effect of two or more independent variables on a dependent variableAllows testing of interactions and contingent conditions

05/03/23Marketing 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

10Ad A Ad B

Women

Men

Bel

ieva

bili t

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.

05/03/23Marketing Research 14

05/03/23Marketing Research 15