Kumar-2011-Research-Methodology_-A-Step-by-Step-Guide-for-Beginners

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Research Methodology
In the experimental group, total change in the dependent variable (Y e
) can be calculated
as follows:
Y e
= (Y '' e
– Y ' e
)
where
Y '' e
= ‘after’ observation on the experimental group
Y ' e
= ‘before’ observation on the experimental group
In other words,
(Y '' e
– Y ' e
) = (impact of programme intervention) ± (impact of extraneous variables) ±
(impact of chance variables)
In the control group, total change in the dependent variable (Y c
) can be calculated as
follows:
Y c
= (Y '' c
-Y ' c
)
where
Y '' c
= post-test observation on the control group
Y ' c
= pre-test observation on the control group
In other words,
(Y '' c
–Y ' c
) = (impact of extraneous variables) ± (impact of chance variables)
The difference between the control and experimental groups can be calculated as
(Y '' e
– Y ' e
) – (Y '' c
– Y ' c
),
which is
{(impact of programme intervention) ± (impact of extraneous variables in experimental groups)
± (impact of chance variables in experimental groups)} - {(impact of extraneous variables in
control group) ± (impact of chance variables in control group)}
Using simple arithmetic operations, this equals the impact of the intervention.
Therefore, the impact of any intervention is equal to the difference in the ‘before’ and ‘after’
observations in the dependent variable between the experimental and control groups.