This presentation explains different designs used while conducting experimental researchers in social and behavioral sciences. It discusses various designs under pre-experimental designs, true experimental designs and quasi experimental designs. It also talks on the effectiveness of this designs in controlling the threats to internal and external validity.

1. Experimental Designs
© V. Singh
Vikramjit Singh, PhD

2. • Experimental Research is in which-
– conditions are controlled
– so that 1 or more independent variables
– can be manipulated to test a hypothesis
– about a dependent variable.
•It Allows -
– evaluation of causal relationships among variables
– while all other variables are eliminated or controlled.
Experimental Research …… a review..
© V. Singh

3. Symbol System for Representing
Experimental Designs
X- Exposure of a group to the experimental
treatment or the traditional treatment.
O- Observations or measurement of the dependent
variable.
R- Random assignment of the subjects. The
individuals are randomly assigned to the
experimental and control groups.
© V. Singh

4. Experimental Designs
1. Pre-Experimental Design
2. True Experimental Design
3. Quasi Experimental Design
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5. Pre-Experimental Design
• Pre- Experimental designs are those designs those are very close to a true
experiment but not as perfect as a true experimental design. These designs
provide very poor control over the threats to experiments.
• Many a times these designs are used to provide a base for conducting further
research using a design which is strong enough to control the threats involved.
© V. Singh

6. Pre-Experimental Designs
One Shot Case
Study
One Group pre-
test , post-test
design
Pre-Experimental
Designs
Static Group
Comparison
Design
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7. Pre-Experimental Design- One Shot Case Study
• Symbolic Illustration
Treatment
X Observation
O
How Was my
Class ?
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8. Sources of Invalidity – One Shot Case Study
© V. Singh

9. Pre-Experimental Design- One Group pre-
test, post-test Design
Treatment
X Observation
O
Observation
O
• Symbolic Illustration
© V. Singh

10. Sources of Invalidity – One Group pre-test, post-test Design
© V. Singh

11. Pre-Experimental Design- Static Group
Comparison Design
Treatment
X1
Observation
O
Treatment
X2
Observation
O
Experimental
Group
Control
Group
Symbolic
Illustration
© V. Singh

12. Sources of Invalidity – Static Group Comparison Design
© V. Singh

13. True Experimental Design
This category consists of designs
which are the strongest in controlling
the threats . The specific character of
the designs in this type is that there is
always the presence of control group
and the selection and assignment of
the subjects in the experimental and
control group is random.
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14. True Experimental Designs
Posttest only
Control Group
Design
Pretest-Posttest
control group
Design
True
Experimental
Designs
Solomon Four
Group Design
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15. Observation
Treatment
Observation
True Experimental Design- Posttest only
Control Group Design
Treatment
X1 O
X2 O
Experimental
Group
Control
Group
Symbolic Illustration
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16. Sources of Invalidity – Posttest only Control Group Design
© V. Singh

17. Pre-Experimental Design- Pretest Posttest
Control Group Design
Treatment
X1
Observation
O
Experimental
Group
Control
Group
Symbolic Illustration
Treatment
X2
Observation
O
Observation
O
Observation
O
© V. Singh

18. Sources of Invalidity – Pretest Posttest Control Group Design
© V. Singh

19. True Experimental Design-Solomon Four Group
Design
Symbolic
Illustration
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20. Interpretation from Solomon Four – Group Design
Experimental Group 1 : R O1 X1 O2
Control Group 1 : R O3 X2 O4
Experimental Group 2 : R X1 O5
Control Group 2 : R X2 O6
Effect of Independent Variable: (O2-O4) or (O5-O6)
Effect of Pretesting: (O4-O6)
Effect of Pretesting & Measuring: (O2-O5)
Effect of Random Assignment: (O1-O3)
© V. Singh

21. Sources of Invalidity – Solomon Four – Group Design
© V. Singh

22. Quasi- Experimental Design
As per the dictionary meaning of Quasi , Quasi- Experimental
Design are designs very much closer to true experimental designs
but not as perfect in controlling the threats to internal and external
validity.
The very much closeness to these designs with true experiment
and the practicality of the designs makes these designs the most
used upon designs during conducting experiments in social
sciences.
© V. Singh

23. Quasi- Experimental Designs
Non equivalent
Control Group
Design
Time Series
Design
Quasi-
Experimental
Designs
Counterbalanced
Design
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24. Quasi-Experimental Design- Non equivalent
Control Group Design
Treatment
X1
Observation
O
Experimental
Group
Control
Group
Symbolic Illustration
Treatment
X2
Observation
O
Observation
O
Observation
O
© V. Singh

25. Sources of Invalidity – Non equivalent Control Group Design
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26. Quasi-Experimental Design- Time Series Design
Treatment
X
Symbolic Illustration
Observations
O1
Observations
O2 O3 O6
O4 O5
Control Group
Experimental Group
© V. Singh

27. Sources of Invalidity – Time Series Design
© V. Singh

28. Quasi-Experimental Design-
Counterbalanced Design
Symbolic Illustration
Treatment
X1 Observation
O Treatment
X2
Observation
O Treatment
X3 Observation
O
Treatment
X3 Observation
O Treatment
X1
Observation
O Treatment
X2 Observation
O
Treatment
X2 Observation
O Treatment
X3
Observation
O Treatment
X1 Observation
O
© V. Singh

29. Sources of Invalidity – Counter Balanced Design
© V. Singh

30. Catch me up for Other Experimental
Design….
Factorial Designs
Single Subjects Designs
Statistical Designs
Completely Randomized Designs
Randomized Block Designs
Latin Square Designs
© V. Singh

31. Catch me up for Other Experimental
Design….
Any questions?
You can find me at:
singhvikramjit@hotmail.com
Mob: +91-9438574139
© V. Singh