moderation and iteraction

1. Moderators
Michael Sony
emailofsony@gmail.com
Worshop on Research Methods at GUDMS

2. Terminology
• Criterion Variable (dependant variable)
• Predictor Variable ( Independent variable)
y = criterion
variable
x = predictor
variable
Worshop on Research Methods at GUDMS

3. Moderation
• A third variable changes the relationship
between two related variable.
In other words
• Relationship between two variables changes
with the level of another variable of construct
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4. Independent
variable
(predictor)
Moderating
variable
Dependant
variable
(criterion)
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5. Mathematical representation
Y = a + b. x1 + c.x2 + d.x1x2
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6. • Moderation
Predictor
Criterion
Moderator
Interaction Significant
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7. Types of Moderators
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8. • Pure Moderator
Predictor
Criterion
Moderator
Interaction
Not Significant
Significant
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9. • Quasi Moderator
Predictor
Criterion
Moderator
Interaction
Significant
Significant
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10. Moderator v/s Mediation
• Mediation – significant relationship of
mediator between independent variable and
dependant variable
IV
Mediator
DV
Worshop on Research Methods at GUDMS

11. Moderator v/s Mediation
• Moderator – significant / no significant
relationship between moderator variable and
dependant variable
Interaction
IV
Mod
DV
Χ
Aiken, L. S., & West, S. G. (1991). Multiple regression: Testing and interpreting
interactions. Sage.
Worshop on Research Methods at GUDMS

12. Moderator v/s Mediation
• Mediator variable is consequent of predictor
variable.
IV
Mediator
DV
Worshop on Research Methods at GUDMS

13. Moderator v/s Mediation
• Moderator variable is at same level as
predictor variable.
Moderator
IV
DV
x
Worshop on Research Methods at GUDMS

14. Classification of Moderator
• Non- Metric moderators ( Gender, race etc)
• Metric Moderators (level of reward,
motivation etc)
Worshop on Research Methods at GUDMS

15. Aiken and West Approach
• Step1 : Regress on dependant variable the
independent variable and moderator variable
• Step2: Center all the continuous variables
• Step3: Multiply the independent and
moderator variable and create interaction
variable
• Step 4: Regress on dependant variable the
independent variable ,moderator variable and
Interaction variable
Aiken, L. S., & West, S. G. (1991). Multiple regression: Testing and interpreting
interactions. Sage. Worshop on Research Methods at GUDMS

16. Aiken and West Approach
• Step 5: Check whether interaction variable is
significant else no Moderation
• Step 6: ΔR2
• Step 7 : If moderator is continuous variable
classify into meaning full groups or classify the
same based at ± >= 1 σ level
• Step8: Plot Graphs and interpret the same
with significant slopes
Worshop on Research Methods at GUDMS

17. Example 1
• Students who were attending an orientation before
starting their first year of college.
• Students were asked to report on the number of minor
stressful events (labeled hassles) that they had recently
experienced, and also to report on their perceived level
of social support.
• They then completed a symptom checklist on the
number of symptoms they had experienced in the past
month.
• For this part of the study there were complete data on
56 participants.
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18. Example 1
Hassles
Support
symptoms
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19. Example 2
Attitude
towards
coworkers
Job
Satisfaction
Gender
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20. Thank you
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