The nature of experimentation

1. THE NATURE OF
EXPERIMENTATION

2. Definition
•Experimentation involves the manipulation
of one or more variables by the
experimenter in such a way that its effect
on one or more other variables can be
measured.

3. Independent Variable & Dependent Variable
•A variable being manipulated is called the
independent variable.
•A variable that will reflect the impact of
independent variable is called a
dependent variable.

4. Treatment & Control Group
•A group exposed to a manipulation of the
independent variable is known as a
treatment group.
•A group in which the independent variable
is unchanged is called the control group.

5. Randomization or Matching
•Randomization involves randomly
assigning subjects to treatment or control
groups.
•It is to ensure that the independent
variable is the only variable that differs
between the groups.

6. Purpose of Experimentation
•To establish and measure causal
relationships among the variables.
•To control other potential causal factors
(extraneous variables).

7. Potential Sources of Experimental
Error
•Premeasurement
•Interaction Error
•Maturation
•History
•Instrum,entation
•Selction
•Mortality
•Reactive error
•Measurement timing
•Surrogate situation