Causal Design and Experimentation

1
Chapter 8

• Causal Design and Experimentation

2
Typical Marketing Research Design
Observation at time 1 e.g., plan to buy milk
Treatment e.g., got milk ad

• O1 X O2

Observation at time 2 e.g., want milk
3
Central Issues for Research (1)

• The Internal (to the study) Relationship Issue
• Is there a relationship (covariation) between
  the two variables?
• Is the relationship causal

4
Central Issues for Research (2)

• The External (to the real world) Relationship
  Issue
• how generalizable (time, people, settings)
  are the relationships

5
The Internal Relationship Question

• Internal Validity whether the manipulation of
  the independent variable caused the effects in
  the dependent variable

6
Three criteria of Internal Validity

• Covariation (concomitant variation)
• are IV and DV correlated
• Temporal precedence
• does IV occur before or with DP?
• Lack of other possible causes

7
Threats to Internal Validity (Extraneous
Variables-1)

• History events between to measurements other
  than the treatment
• Maturation changes within respondents as a
  function of time
• Testing
• main effects of taking one test on scores on
  second test
• interaction effect effect of testing on
  receptiveness to treatment

8
Threats to Internal Validity)(Extraneous
Variables-2)

• Instrumentation Changes in the test or the
  observers used
• Statistical regression effect of groups
  selected bases on extreme scores
• Selection biases resulting from differential
  assignment

9
Threats to Internal Validity)(Extraneous
Variables-3)

• Mortality differential loss of subjects
• Selection-maturation interaction differential
  maturation of groups based on selection

10
The ExternalRelationship Question

• External Validity whether an observed causal
  relationship can be generalized across different
  persons, settings, and times

11
Pre-experimental Designs

• One-Shot Posttest only Design (case study)
• X O1
• Posttest-Only Design
• TG X O1
• CG O2
• One-Group Pretest-posttest design
• O1 X O2

12
True Experimental Designs

• Pretest-Posttest Control Group Design
• EG R O1 X O2
• CG R O3 O4
• Posttest-Only Control Group Design
• EG R X O2
• CG R O4

13
True Experimental Designs (2)

• Solomon Four_Group Design
• EG1 R O1 X O2
• CG1 R O3 O4
• EG2 R X O5
• CG2 R O6

14
Quasi-Experimental Designs

• Pretest-Posttest Non-equivalent Groups Design
• TG O1 X O2
• CG O3 O4
• Time-Series Design
• O1 O2 O3 O4 O5 X O6 O7 O8 O9
• Multiple Time Series Design
• TG O1 O2 O3 O4 O5 X O6 O7 O8 O9
• CG O1 O2 O3 O4 O5 O6 O7 O8 O9