Types of Experimental research design

1. EXPERIMENTAL RESEARCH DESIGN
Sanghamitra Jena
PhD Scholar
LNIPE, Gwalior

2.  Experimental design is the process of carrying out research in an objective
and controlled fashion so that precision is maximized and specific
conclusions can be drawn regarding a hypothesis statement. (Bell, 2009)
 Experimental research is a scientific approach to research, where one or
more independent variables are manipulated and applied to one or more
dependent variables to measure their effect on the latter.
 The types of experimental research design are determined by the way the
researcher assigns subjects to different conditions and groups.

3.  There are three main types of experimental research design
I. Pre-experimental
II. Quasi-experimental
III. True experimental research

4. Pre-experimental Research Design
 The pre-experimental research design is the most basic type of
experimental research design in statistics. This design do not use any
randomization procedure to control the effect of extraneous variables.
 No control over extraneous variable
 The pre-experimental research design is further divided into three types
I. One-shot Case Study Research Design
II. One-group Pretest-posttest Research Design
III. Static-group Comparison

5. I. One-shot Case Study Research Design
 In this research design a single experimental group is exposed to a
treatment and observations are made after the implementation of that
treatment.
 No control group
 There is no random assignment of subjects to the experimental grp
 Design
Exp grp Treatment Post Test
Example- Effect of counselling session on the behaviour of selected students
who all are academically weak.

6. II. One-group Pretest-posttest Research Design
 Research design combines both posttest and pretest study by carrying out a
test on a single group before the treatment is administered and after the
treatment is administered. With the former being administered at the
beginning of treatment and later at the end.
 No control Group
 Offers comparison of the same individuals before and after the treatment.
 Design
Exp grp Pre Test Treatment Post test
Example- Effect of specific training on the performance of the trainees
(measurement before and after the training session)

7. III. Static-group Comparison
 In a static-group comparison study, 2 or more groups are placed under
observation, where only one of the groups is subjected to some treatment
while the other groups are held static. All the groups are post-tested, and the
observed differences between the groups are assumed to be a result of the
treatment.
 No pre measure is taken. Both groups are measured only after the treatment
has been presented.
 Exp grp Treatment Post Test
Control Grp Post Test
Example- Effect of training on the employees performance level and then
difference with the group who have not received any training

8. Quasi-experimental
 The word “quasi” means partial, half, or pseudo. Therefore, the quasi-
experimental research bearing a resemblance to the true experimental
research, but not the same.
 In a quasi-experimental design, the participants of the groups are not
randomly assigned. So, the researcher cannot make a cause-or-effect
conclusion.
I. Time series
II. Multiple time series
III. Non eqivalent control group Design

9. I. Time series
 In this design only one group is evolved but many observations will be
recorded to see the effect of treatment or change due to the treatment. Many
test are taken followed by a treatment which is again followed by many post
tests.
 Giving treatment to the same group.
 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.
Design Experimental Group :
Exp group O1 O2 O3 Treatment O1 O2 O3

10. II. Multiple time series
 Measuring of two groups for a certain variable for a predetermined period.
 Giving one group treatment (The Experimental group)
 Measuring the two groups again for the variable for a predetermined period.
 Possible change may be attributed to the treatment.
III. Nonequivalent 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.
 Both groups are selected without randomization
 Experimental group receives treatment

11. Exp group Treatment Post Test
Pre Test
Control group Pre Test Post Test
True Experimental Design
 True experimental design is the most accurate form of experimental
research in which participants are randomly assigned to
experimental and control groups.
 Types
I. Post Test Randomised Group ERD
II. Pre Post test Randomised ERD
III. Solomon four group Design

12. I. Post Test Randomised Group ERD
 Both groups present(Exp grp and control grp)
 Participants randomly assigned to both grp
 Groups are not pre tested on Dependent variable
 Both groups post tested to find the effect of treatment and no pre test
Exp grp Treatment Post Test
Control group Post Test
Example-
Awareness camps for smokers and findingits effects on smoking attitude
Random group with smokers of same level

13. Control grp- R- No Awareness camp- Post test( 50)
Exp grp- R- Awareness camp- Post test(20)
 Effect of treatment = 20-50= -30( decrease in tendency towards
smoking(effectiveness)
II. Pre Post test Randomised ERD
 Both experimental and control grp present
 Participants Radomly assigned to both grp and both grp Pre tested on
Dependent variable
 Then treatment in exp grp and control condition in Control group
 Both grp post tested to find the effect of treatment on dependent variable

14.  Design:
Experimental Group : Random Group - Pre Test --Treatment – Post Test
Control Group : Random Group - Pre Test -- No Treatment – Post Test
III. Solomon four group Design
 This type of design is used on large population only. The groups are
randomly divided followed by the pre test which is followed by the
treatment and the final test.
 This can also includes post test only or pre test post test random design
both depending upon the situation separately or simultaneously. The
comparison will be made between the group vertically in case of pre test
and post.
 Design:
Experimental Group 1: Random Group - Pre Test --Treatment – Post Test

15. Control Group 1: Random Group - Pre Test – Post Test
Experimental Group 2: Random Group – No Pre Test -- Treatment – Post Test
Control Group 2: Random Group – No Treatment -- No Treatment – Post Test