Experimental Design Methods

Experimental Design Methods

Introduction
The Pretest-Post-test design is an experimental design that has subjects being randomly assigned
to either the experimental or the control groups 1. Pretest is conducted for both groups on the
independent variable. Treatment is applied on the experimental group while the control group
receives no treatment. Both the experimental and the control groups are post-tested to evaluate
the impact of manipulation of the independent variable on the dependent variable.
However, an advanced form of this design which allows for testing of two or more hypotheses is
the factorial design 2. The factorial design allows for manipulation of two or more independent
variables to elicit response on the dependent variable. Therefore, two or more hypotheses can be
tested on a single experiment.
The experimental design for this task is therefore a pre-test-post-test design since it has only one
factor. The factor involved is the groups (experimental or control). This method can be applied in
scientific research to help in determining how effective the research would be 3. It can be seen as
a clear way of knowing the accuracy of the question at hand. The experimental design method is
useful in the investigation of the effectiveness of research in many fields such as in agriculture,
medical, and education. In education, researchers can use the method to help them in the
observation of a particular occurrence and recommend the course of action to be taken in
consideration to the result from the research carried out 4.
The table indicates the pre-test-post-test control group method where subjects have been
randomly assigned to the treatments and control groups. Pre - test analysis on the independent
variable for both the experimental and control groups while post - test analysis is only carried out
on the experimental group since the control group is not subjected to treatment.
1
Reason why the above design is a good experimental design
1 Hall Ashley, Experimental Design: Design Experimentation (2011
2 Siddiqui, Adaptive sequential experimentation technique for 3³ factorial designs based on revised simplex search
(2010)
3 Wang, Applied scientific research (2012).
4 Ping, Jian, Data Processing in Scientific Research Performance Evaluation of University Based on DEA and
Supervision Measures: Advanced Materials Research (2014).

The Pre- Test Post-Test design is a good experimental design for investigating the effectiveness
of the inquiry method in enhancing Inductive reasoning among primary school children. This is
because the Pre- Test Post- test experimental research design allows for the random selection of
groups 5. In this design, pupils will be randomly selected and put into either the experimental
group or control group. The pupils who fall in the experimental group are subjected to the
treatment, which is the Inquiry method of teaching. However, pupils in the control group are not
taught using the Inquiry method.
Pre- test analysis is carried out on the experimental and control groups to assess their
performance. Post- test analysis is also carried out to investigate the effect of the Inquiry method
of teaching on pupils’ academic performance.
The Pre- Test Post- test design eliminates the possibility of bias in selection of subjects into
groups due to the random assignment of pupils to the Inquiry method of teaching. This type of
research design also eliminates the effects of confounding since only one factor is involved 6.
The effect of only the Inquiry method of teaching in enhancing inductive reasoning among
Primary school children is evaluated.
Hypotheses for the study;
Since the study tries to investigate the effectiveness of the Inquiry method of teaching in
enhancing Inductive reasoning on primary school children, we compare the post- test results of
the experimental group and those of the control group. We therefore formulate the following
Hypotheses:
1. H0: The distribution of responses is the same across the 4 weeks-time period.
2. H0: Pupils who are subjected to the Inquiry method of teaching do not perform differently
from pupils who are not subjected to the inquiry method of teaching in terms of inductive
reasoning.
2
Threats that may affect the internal validity of the experiment
25 Hildebrand, Martin, Random walks on random simple graphs (2016).
6 Cinelli, Francesco, Confounding in field experiments: (2012).