1.
QUASI
EXPERIMENTAL
RESEARCH DESIGN
DR. MAHESWARI JAIKUMAR
2.
INTRODUCTION
• Quasi experimental research design
involves the manipulation of
independent variable to observe the
effect on dependent variable.
• The study unlike true experimental
study lacks at least one of the three
cardinal characteristic
(Randomization, Control)
3.
• Quasi experimental designs have an
element of manipulation.
• Quasi experimental designs are
generally used to establish the causality
(effect of independent variable on
dependent variable) in situations where
researchers are not able to randomly
assign the subjects to groups for various
reasons.
4.
CHARACTERISTICS
• Manipulation of the independent
variable to observe the effects of
the dependent variables.
• It lacks at least one of the two other
essential characteristics of the true
experiment.
5.
• Quasi independent variables are used
instead of true independent variables
and independent variable is not
manipulated in complete controlled
situations.
6.
TYPES
There are several types. The two
important types are as follows:
1. NON RANDOMIZED CONTROL
GROUP DESIGN.
2. TIME SERIES DESIGN
7.
NON RANDOMIZED CONTROL
DESIGN
• Is also known as “non equivalent
control group design”.
• This design is identical to the pre test-
post test group design, except there is
no random assignment of the study
subjects in experimental and control
groups.
8.
• In this design experimental and
control groups are selected without
randomization.
• Dependent variables are observed
in experimental as well as control
groups before the intervention.
9.
• Later the experimental group receives
treatment, following which the post test
observation of dependent variable is
carried out for both the groups to assess
the effect of the intervention or
treatment on experimental group.
10.
NON RANDOMIZED CONTROL
GROUP DESIGN
EXP GROUP
CONTROL
GROUP
PRE TEST
PRE TEST
TREATMENT POST TEST
POST TEST
11.
TIME SERIES DESIGN
• Time series design is useful when the
researcher intends to measure the
effects of a treatment over a long period
of time.
• The researcher would to continue to
administer the treatment and measure
the effects a number of times during the
course of the experiment.
12.
• In a single - subject research, in which
the researcher carries out an
experiment on an individual or on a
small number of individuals, ……..by
alternating between administering and
then withdrawing the treatment to
determine the effectiveness of the
intervention.
13.
TIME SERIES DESIGN
EXP GROUP O2O1 O2 O3 O1 O3TREATMENT
14.
EXAMPLE
• Measurement of a learner’s
performance in a college on weekly
basis and then introducing a new
teaching technique. Then again
measuring on weekly basis.
15.
ADVANTAGES
• Quasi experimental designs are more
frequently used because they are more
practical and feasible to conduct
research.
• Where the sample size is small, and
where randomization & availability of
control group is not possible, this design
is preferred.
16.
• Quasi experimental design is more suitable
for real natural world setting than true
experimental designs.
• This design allows the researchers to
evaluate the impact of quasi independent
variables under naturally occurring
conditions.
• In some cases hypotheses are practically
answered through this design.
17.
DISADVANTAGES
• In this design there is no control over
extraneous variables influencing the
dependent variable.
• The absence of a control group and absence
of control over the research setting makes
the result of this design less reliable and
weak for the establishment of causal
relationship between independent &
dependent variable.
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