This document discusses experimental research methods. It defines experimental research as a method to establish causal relationships between variables. There are three types of experimental research: true experimental research, quasi-experimental research, and pre-experimental research. True experimental research uses random assignment and controls for interfering variables. Quasi-experimental research assigns treatments but cannot randomly assign participants. Pre-experimental research only uses a pre-test and post-test without a control group. The document also discusses threats to validity in experimental research like history, maturation, testing, and others that must be controlled.

1. EXPERIMENTAL RESEARCH
ARIF JUNAIDI (12510174006)
IMROATUL MUFIDAH (12510174022)
TBI 1 A
Lecturer : Dr. H. Nursamsu, M. Pd

2. EXPERIMENTAL RESEARCH
• Experimental research is a powerful research
method to establish cause and effect
relationship involving two or more variables.
• The variable becomes the cause (independent
and the other variable become the effect.

3. TYPES OF EXPERIMENTAL RESEARCH
• TRUE EXPERIMENTAL RESEARCH
• QUASI-EXPERIMENTAL RESEARCH
• PRE-EXPERIMENTAL RESEARCH

4. TRUE EXPERIMENTAL RESEARCH
• The researcher has access to random selection
of the samples and random assignment of the
samples into experimental and control groups
to ensure the equivalence of groups and to
control for many interfering variables that
might otherwise contaminate the results of
the investigation.

5. TRUE EXPERIMENTAL RESEARCH
DESIGN
• Pretest-Posttest Control-Group Design
or
• Posttest-only Control-Group Design

6. PROCEDURE FOR PRETEST-POSTTEST CONTROL-
GROUP DESIGN
• Define population (e.g. all registered first year
students of SMAN 1 Malang)
• Define sample randomly (e.g.100 students)
and select randomly one half of the members
of the sample and assign them into group A
and assign the rest into group B (e.g. 50
students of group A and 50 students of group
B

7. PROCEDURE FOR PRETEST-POSTTEST
CONTROL-GROUP DESIGN
• Give pretest to group A and B to assess their
level of knowledge or skills.
• Analyze the results of the pretest to ensure
that the average scores of the two group are
not significantly different.
• Randomly assign one of the groups into the
Experimental group and the other one into
the Control group.

8. PROCEDURE FOR PRETEST-POSTTEST
CONTROL-GROUP DESIGN
• Give the experimental treatment to the
experimental group and the control treatment
to the control group.
• Give a posttest to assess the results of the
treatments of both groups.
• Compute the difference between the average
score of the experimental group and the
control group.

9. QUASI-EXPERIMENTAL RESEARCH
• In educational settings, very often it is not
possible to select the sample randomly out of
all the population students and assign to
different classes.
• When the researcher can only assign
randomly different treatments to two
different classes, the researcher uses quasi-
experimental research design.

10. PROCEDURE IN QUASI-EXPERIMENTAL
RESEARCH
• Define population (e.g. all registered first year
students of SMAN 1 Malang).
• Selects two classes out of all the existing classes
which are of equivalent level (e.g. class 1-C and
class 1-F of SMAN 1 Malang).
• Randomly select one of the classes into
Experimental Group and the other one into the
Control Group (e.g. class 1-C as the Experimental
Group and class 1-F as the Control Group).

11. QUASI-EXPERIMENTAL RESEARCH
• In educational settings, very often it is not
possible to select the sample randomly out of
all the population students and assign to
different classes.
• When the researcher can only assign
randomly different treatments to two
different classes, the researcher uses quasi-
experimental research design.

12. PROCEDURE IN QUASI-EXPERIMENTAL
RESEARCH
• Give the experimental treatment to the
experimental group and the control treatment
to the control group.
• Assess the results of the treatments of both
groups.
• Compute the difference between the average
score of the experimental group and the
control group.

13. PRE-EXPERIMENTAL RESEARCH
• Sometimes an experimental research is
conducted without a control group.
• In this research, the group is given a pre-test
before the experimental treatment.
• After the treatment is finished, the post test is
administered to see the achievement.
• The effectiveness of the instructional
treatment is measured by comparing the
average score of the pretest and the post test.

14. PRE-EXPERIMENTAL RESEARCH
• When the post test average score is significantly
higher than the average score of the pretest, then
it is concluded that the instructional treatment is
effective.
• Another name for this pre-experimental research
design is One-Group Pretest-Posttest Design.
• This pre-experimental research can be done to
investigate, for example, the effectiveness of
bilingual classes in Science classes in SMAN 1
Malang.

15. THREADS to VALIDITY in
EXPERIMENTAL RESEARCH
• A researcher must make sure that the different
treatments are really different, while the other things
are kept the same.
• Therefore the key problem in experimentation is
how to establish suitable control for the threats to
experimental validity which come from unexpected
interfering variables in the process of experiments.

16. HISTORY
When the experimental treatment is developing more
motivation to the students in the experimental group,
then the motivation may develop positive attitude of the
students toward learning, if the achievement of the
experimental group is better than that of the control
group, then the difference in achievement may not only
be caused by the different treatment but also by the
different motivation and attitude of the students.

17. MATURATION
Maturation is related to biological and
psychological development of the students
while the experiment is in progress.

18. TESTING
In the experiment using pretest and posttest,
if the posttest user the same instrument with
the pretest, the students might learn from the
pretest.

19. INSTRUMENTATION
When the researcher observes the same students’
performance the second time after the treatment,
he or she might not be able to give as objective
rating to the quality of the students’ performance
as the rating given in the first observation simply
because the researcher may expect
(subconsciously) a more favorable change in the
students’ performance.

20. STATICTICAL REGRESSION
Statistical regression happens because
usually students with extremely high score or
extremely low scores tend to have a change
in their posttest scores toward the mean.

21. EXPERIMENTAL MORTALITY (ATTRITION)
This threat happens because some members of
the sample with draw from the experimental
program for whatever reasons, because they
are sick so they cannot attend the post test,
they do not like the treatment so they quit the
class, the move to another school, etc.

22. SELECTION – MATURATION INTERACTION
If the experimental treatment and the control
treatment are conducted at different schools
which have different admission policy so that the
members of the experimental group are on the
average six months older than the average age of
the control group.

23. EXPERIMENTAL TREATMENT DIFFUSION
If some members of the control group borrow and
use the instructional materials which are supposed
to be used only by the members of the
experimental group, or some of the members of
the control group do the assignments which are
supposed to be done only the members of the
experimental group.

24. COMPENSATORY RIVALRY BY THE CONTROL GROUP
When the members of the control group
perceive that they are in competition with the
members of the experimental group, they
may get highly motivated to win the
competition.

25. RESENTFUL DEMORALIZATION of THE CONTROL GROUP
If the members of the control group perceive
that the members of the experimental group are
receiving more desirable tratments, they may
demoralize themselves so that in the posttest
the control group may perform unusually lower
than normal.

26. EX-POST FACTO or CAUSAL COMPARATIVE RESEARCH
Ex post facto research measures the relationship between
two variables without manipulating the X-variables. While
the experimental research starts from manipulating and
controling the independent X-variables and proceeds to
observing the effect on the dependent variables,the ex
post facto research starts from identifying the existing
conditions in x variable (eg. Sex) and proceeds to fingding
the differences in y variable.

27. RESEARCH PROBLEMS AND OBJECTIVES in EXPERIMENTAL
RESEARCH
EXAMPLE :
Research objective: This study tries to investigate
the effectiveness of the use of language lab in
increasing the students’ listening skill.
Research problem: Do senior high school students
learning listening skill in language lab achieve
better than those students learning listening skill
in conventional classroom?

28. RESEARCH PROBLEMS
EXAMPLE:
Do freshmen students in the English Department graduating
from state senior high schools achieve higher English mastery at
the end of the 1st semester than those graduating from private
senior schools in Malang (main question)
Do male freshmen students in the English Department
graduating from state senior high schools achieve higher English
mastery at the end of the 1st semester than male students in
the same department graduating from private senior schools in
Malang?

29. CONCLUDING REMARK
Experimental research is very powerful in measuring
cause effect relationship of variables. It can be used
to measure the effectiveness of instructional
materials and strategies by comparing with other
instructional materials and strategies. The problem
with the experimental research is in controlling
interfering variables that may lower the validity of
the research findings.