Module 1-Lesson 3: Experimental Design

Experimental research is one of the most known research designs mainly because it is a
classical scientific experiment that is like the activities performed in science classes (Formplus Blog
2020).
Experimental research is used to investigate the cause and effect relationship between the
variables. It is also known as intervention because you do more than just observe the subject. Unlike
in descriptive research, this design manipulates one variable to see if it influences the other variable.
A factor treatment is introduced into the research investigation and the researcher attempt to isolate
the effects of such treatment by means of control (Faltado et al. 2017).
For example, a researcher wishes to find out if incorporating mobile games to a normal class
activity could increase the class performance of the students. Since a researcher induce a certain
change using mobile games, he/she is intervening with normal class activity.

Experimental research is used when:

(1) There is time priority in a causal relationship (cause precedes effect);
(2) to establish the existence of a cause- and- effect relationship between two variables;
(3) You plan to do manipulation with the variables.

Three Main Parts of Experiments

According to Wikibooks (2019) and Colombo Plan Staff College (2018), the most customary
experiments are:

1. Independent and Dependent Variables

• Independent variable. It is a manipulated variable that incurs change in dependent variable.
It is the “experimental stimulus”.
• Dependent variable. It is a variable being studied in the experiment. It is expected to change
when independent variable is manipulated.

2. Pretesting and Post testing

• Pretesting. It is the initial measurement of dependent variables among the participants of the
study.
• Post testing. It is the re-measurement of dependent variables among the participants of the
study after they have been introduced to independent variables.

3. Experimental and Control Group

• Experimental group. This is the group exposed to the influence of intervention or treatment.
This group was used in administering the independent variable.
• Control group. This group is not exposed to any intervention or treatment.
• It is important to keep a close look to both group during experimental period.

Types of Experimental Research Design

As mentioned in the works of Faltado et al. (2017) and Colombo Plan Staff College (2018), below
are the types of experimental research design used in quantitative research.

• Pre-experimental Research Design. This is the simplest form of experimental research design and
usually conducted without a control group. This research design is further divided into three types.

Design 1. One-shot design. This design includes only one group (experimental group) that is exposed
to treatment and sometime after, a posttest is given to determine the effects of the treatment.
 Design 2. One group pretest-posttest design. This design includes only one group (experimental
group) that is exposed to a treatment. The results of the pretest and posttest are compared to
determine the effects of the treatment.

Design 3. Static group comparison design. This design includes two groups (one experimental group
and the other is a control group). Both groups are given a posttest. The posttest results of both groups
are compared to determine the effects of the treatment.

• True Experimental Research Design. This is the most accurate experimental research design. The
distribution of samples for this design must be random. The classification of this design is divided
into three types.

Design 4. Pre-test/ Post-test Control Group Design. This design requires two groups in equal standing
(one control group and one experimental group). Both groups will be given a pre-test. During the
experimental period, only the experimental group will receive the treatment. After the experimental
period, both groups will be given a post-test. Then the researcher may now compare the result of the
post-test of both groups.

Design 5. Posttest-Only Control Group Design. This design includes two groups in equal standing
(one control group and one experimental group). Both groups are not given pretests but both groups
are given a posttest after the exposure of the experimental group to the intervention or treatment.

Design 6. Solomon Four-Group Design. It makes use of four groups in equal standing (two
experimental groups and two control groups). The first two groups are tested using the pretest-
posttest method and the last two
groups are tested using the posttest
only method. After experimental
plan, the posttest results of four
groups are compared.
• Quasi-Experimental Research Design. This design does not include the use of randomization in
assigning the participants of the study. This was used when the setting of the study is impossible
to involve the process of randomization. This design divided into two.

Design 7. Matching only design. The researchers still match the subjects in the experimental group
and control group on some variables but cannot be assured that they are equivalent to others.

Design 8. Time-series design. This design is usually an expansion of the one-group pretest-posttest
design. If the group score essentially the same in the pretests and the consistently improve in the
posttests, the researcher may have more confidence in claiming that the treatment causes the
improvement than if only one pretest and on posttest were given.

Experimental Methods

• Blind Experiment. It is used to ensure the validity of the test. According to Bacli (2019), it
specifically combats two internal validity threats:
• Experimenter Bias – the experimenter expectation causes the study to be biased.
• Participant Bias – The desire of the participants to become “good participants” causes the
study to be biased.

Single Blind Experiment – it is a method where either the participants or the experimenters are blind
to the manipulation being made.
Double Blind Experiment – a method where both the participants and experimenters are blind to the
manipulation being made. One of the researchers act as the coordinator to the participants, but
he/she cannot share the information to other researchers.

Placebo Group – a group of participants being told that they are receiving a treatment, when in fact,
they are not. The result from this group will be compared to the real experimental group. So, if the
experimental group shows better result compared to the placebo group, then the treatment works.
Activity 1: True or False
Directions: Accomplish the following activities in a separate sheet of paper.
Modified True or False. Write T if the statement is correct, if false, change the underlined word/s to
make the statement correct.

____1. The one-shot design includes only one group that is exposed to the treatment and sometime
after a posttest was given.
____2. Static group comparison design includes only one group (experimental group) and done by
giving pretest, treatment, and posttest.
____3. The true experimental research design involves the randomization process.
____4. A group in experimental research that does not receive treatment or intervention is called the
control group.
____5. A group of subjects being lied that they received treatment is called control group.
____6. The static four group design requires four groups (two experimental groups and two control
groups) in equal standing.
____7. Single blind experiment happens when both the participants and experimenters are not
aware of the manipulation being made.
____8. Posttest only group design is a type of experimental research design containing two groups
(experimental group and control group) in equal standing and eliminates the pretesting part.
____9. A group of subjects that receives treatment during the experimental plan is called the
experimental group.
____10. Experimental research is a scientific method that establishes the cause and effect relationship
between the variables.

Activity 2
Directions: Read and analyze the following statements. Choose the letter of the best answer and
write your answer in your notebook.
1. What design is an expansion of the one-group pretest-posttest design where the researcher may
have more confidence in claiming that the treatment causes the improvement than if only one
pretest and one posttest were given?
A. One-shot design C. Posttest-only design
B. Matching only design D. Time-series design
2. Which is TRUE about the experimental research?
A. It generalizes the big amount of data.
B. It is used when your goal is to not intervene with variables.
C. It makes a simple interpretation on the data gathered from the participants of the study.
D. It allows the researcher to make causal inferences between independent variables and a
dependent variable.
3. Which statement best described true experimental research design?
A. It is usually conducted without control group.
B. It is used when randomization is impossible to do.
C. It does not need to have two or more groups of subjects.
D. It involves randomization process in selecting subjects of the study.
4. Which of the following topic needs to use an experimental research design to have more accurate
results?
A. Effectiveness of ECQ in lowering the number of Covid-19 cases
B. Effects of ICT integration to the class performance of the students
C. Influence of social media to the spelling ability of the students in Pasig
D. Comparison of students’ lifestyle before and during the Covid-19 pandemic

5. A group of researchers conducted a study entitled “Raising students’ class performance through
the use of self-learning modules”. They group the student-respondents into two (experimental group
and control group) with equal standing. Both groups were given a pretest. After the exposure of the
experimental group to the treatment, both groups were given a posttest. What type of experimental
research design was applied by the researchers?
A. Posttest-Only Research Design
B. Pre-Experimental Research Design
C. Quasi-Experimental Research Design
D. True Experimental Research Design