**Three Types of Variables **

There are three types of
variables you need to be concerned about when writing a thesis. They are the independent, moderator, and
dependent variables.

**The Independent
Variable**

1. The independent variable is not affected by the other
variables. Its values are independent of changes in the values of other variables.
It determines the values of other variables. The independent variable is manipulated
by the researcher in that the researcher controls whether or not subjects are
exposed to the independent variable.

An
Example is teaching method. It is not
affected by any other variables, in fact it is the
variable that does the affecting.

**Treatments of the Independent Variable**

The
independent variable is controlled by the researcher, by splitting the subjects
into different groups, with each group being associated with a different *treatment*
(or value) of the independent variable.

For Example: If
you want to know if the achievement scores in a class will go up if there is a
change in teaching method, you would divide the students into groups. One group would be taught using a traditional
method of teaching while the second group would be taught using a non
traditional method of teaching. The
teaching method is the independent variable.

**The
Moderator Variable**

2. Moderator
variables are characteristics that influence (moderate) the impact of the
independent or treatment variable upon the dependent variable.

Moderator
variables appear only in studies that include independent and dependent
variables - usually experimental studies.

Baron and Kenny (1998) stated that:

In
general terms, a moderator is a variable that affects the direction and/or
strength of the relation between an independent or predictor variable and a
dependent or criterion variable. Specifically within a correlational
analysis framework, a moderator is a third variable that affects the zero-order
correlation between two other variables. In the more familiar analysis of
variance (ANOVA) terms, a basic moderator effect can be represented as an interaction
between a focal independent variable and a factor that specifies the
appropriate conditions for its operation. (*p. 1174)*

When
you have divided the subjects into two groups, you can further divide them into
age, sex, or class such as divergent learners, at-risk students, and social
economic status. All of these factors are moderator variables.

**The Dependent Variable**

3. The
dependent variable is the variable affected by another variable the independent
variable. The dependent variable is the variable that you believe might be
influenced or modified by some treatment or exposure. It may also represent the
variable you are trying to predict.

The
dependent variable is measured to determine if the manipulation of the independent
variable had any effect. The new value of the dependent variable is *caused*
by and *depends *on the value of the independent variable.

The
dependent variable is sometimes called the outcome variable because it is
measured and recorded by the researcher.
The dependent variable depends on what the subject will do. The dependent variable is always what you are
trying to explain; it is always the object of the research.

For example:

You
want to see how a change in treatment (teaching method) will affect achievement
scores of students. The achievement
scores are the dependent variable.

**Group A Group B**

**Traditional Non-Traditional**

**Teaching Method Teaching
Method**

**Gender**

**Variables**:

__Independent variables__: Method of
Teaching

Levels:
Traditional Method vs. Non-

Traditional
Method

__Moderator Variable__: Gender

Levels: Male vs. Female

__Dependent Variable: __ Student Achievement

The control will be the same teacher teaching the same students throughout the course.