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QUANTITATIVE TECHNQUES
Presentation on:
Moderators and Mediators
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Types of variable
The classification of variable is done in 3
different ways:
1. The causal relationship
2. The design of the study
3. The unit of measurement
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From the viewpoint of causation
Investigating a causal relationship, four set of
variable may operate:
1. Change variable
2. Outcome variable
3. Variable that affect the link4. Connecting or linking variable
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Independent variable:
Dependent variable
Extraneous variable Intervening variable
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From the viewpoint of unit
measurement
There are two ways of categorizing variable:
Unit of measurement is categorical (as innominal and ordinal scale) or continuous innature (as in interval and ratio scales)
Unit of measurement is qualitative (as innominal and ordinal scales) or quantitative innature (as in interval and ratio scales).
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Categorical Variables
Categorical variable can be of three types:
Constant variable Dichotomous variable
Polytomous variable
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Categorical variable
Constant variable: can have only one value or category
Dichotomous variable: can be divided only into twocategories e.g: yes/no , good/bad , rich/poor
Polytomous variable: can be divided into more thantwo categories e.g: Religion (Christian, Muslim, Hindu);political parties (Labor, Liberal, Democrat); attitudes
(strongly favorable favorable, uncertain, unfavorable,strongly unfavorable)
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Continuous Variable
They have continuity in their measurement.
For example age, income and attitude score.
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Main theme of the Presentation
Differentiate between two often-confused
functions of third variables that are:- Moderator
- Mediator
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Moderator
A moderator is a qualitative (e.g., gender, race,
class) or quantitative (e.g., level of reward)
variable that affects the direction and/or
strength of the relation between an
independent or predictor variable and a
dependent or criterion variable.
A variable that shows how relationship of
interest change under different circumstances.
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Mediator
Mediator variable is one that explains the
relationship between the two other variables.
A variable that comes in between the othervariables and affect one another.
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Moderator andMediator are often use
interchangeably
It is not at all uncommon for social
psychological researchers to u, the terms
moderator and mediator interchangeably.
Example: Reuben M. Baron and David A.
Kenny criticized social researchers that they
use it interchangeably. Harkins and William
(1980), identified the impact of identifiabilityon social loafing by observing that it
moderates social loafing and within same
paragraph proposed that it is a important
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The Nature of Moderators
Moderator can be qualitative (gender, race,
class) or can be quantitative (level of reward)
It affect the direction between dependentvariable and independent variable
It affect strength of relationship between
dependent variable and independent variable
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The Nature of Moderators
That factor which is measured, manipulated,
or selected by the experimenter to discover
whether it modifies the relationship of the
independent variable to an observed
phenomenon. It is a special type of
independent variable.
The independent variable's relationship withthe dependent variable may change under
different conditions. That condition is the
moderator variable
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Example
Smoking
(Assumed cause)
IV
Cancer
(Assumed
effect)
DV
Age of person
(Moderator)
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Smoking
(Assumed cause)
IV
Cancer
(Assumed
effect)
DV
Duration of Smoking
(Moderator)
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Example of Moderator
Behavioral therapy works better for males and
cognitive therapy works better for females. In
this case, gender is the moderator variable.
The relationship be type of therapy
(behavioral versus cognitive) and
psychological relief is moderated by gender.
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Cognitive
Therapy (female)
Behavioral
Therapy (male)
PsychologicalRelief
Gender
(moderator)
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Diagrammatic display
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MEDIATORS
Mediator variables are also called
Intervening variables
Process variableConnecting variables
Linking variables
Intermediary variables
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In certain situations the relationship between
an IV and DV cannot be established without
the intervention of another variable.
Intervening variables link the IV and the DV.
Mediators give us information on why or bywhat mechanism X causes Y. while moderators
tell when and under what conditions X causes
Y.
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Example
Income longevity needs
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Intervening variables theoretically affect the
observed phenomenon but cannot be seen,
measured or manipulated; its affect must be
inferred from the effects of independent and
moderator variables on the observed
phenomenon.
E.g. A promotion campaign will increase thesavings activity, especially when free prizes are
offered. The results come from enhancing the
motivation to save.
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Path c'is called the direct effect. The
mediator has been called an intervening or
process variable. Complete mediation is the
case in which variable X no longer affects Y
after M has been controlled and so path c'is
zero.
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Note that a mediational model is a causal
model. For example, the mediator ispresumed to cause the outcome and not vice
versa.
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The general test for mediation is to examine
the relation between
the predictor and the criterion variables, the relation between the predictor and the
mediator variables,
and the relation between the mediator andcriterion variables.
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Mediation implies that the IV affects the
mediator, and then the mediator affects theDV.
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Example
educational level -----> occupational type -----> income level
employers will not pay you just because you
have a degree, in fact, it is the job you obtain
that pays the salary. The job is the intervening
or mediating variable between educational
level and income level.
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THANK YOU