Experimental research aims to investigate cause-and-effect relationships between variables by manipulating the independent variable and comparing experimental and control groups. It differs from other research in that the researcher establishes different treatments to study their effects. True experimental designs use random assignment of subjects to groups to control for threats to internal validity. Poor experimental designs do not allow for comparison between groups and cannot determine what causes observed effects.

1. EXPERIMENTAL RESEARCH
CHAPTER 13
Presented by :
Nurul Ain binti Abd Manan 2013160689
Nor Zakiah binti Ismail 2013741249
Siti Khalijah binti Zainol 2013977165

2.  Traditional type of research
 EXPERIMENTAL RESEARCH concerns relationships between
variables
 Purpose is to investigate cause-and-effect relationships among
variables
• Experimental groups vs. control groups
• Each group of participants receives a different treatment
• Always involves manipulation of the independent variable
 The researcher actually establishes different treatments and then
studies their EFFECTS, results from this type of research are
likely to lead to the most clear-cut interpretations
EXPERIMENTAL RESEARCH

3. STEPS IN
EXPERIMENTAL RESEARCH
 State the research problem
 Determine if experimental methods
apply
 Specify the independent variable(s)
 Specify the dependent variable(s)
 State the tentative hypotheses
 Determine measures to be used
 Pause to consider potential success
 Identify intervening (extraneous)
variables
 Formal statement of research
hypotheses
 Design the experiment
 Final estimate of potential success
 Conduct the study as planned
 Analyze the collected data
 Prepare a research report

4. UNIQUENESS
EXPERIMENTAL RESEARCH
Two ways in which EXPERIMENTAL RESEARCH differs from
other educational research.
Researcher manipulate the independent variable :-
1. Decide the nature of the treatment
- to whom it is to be applied
- to what extent
2. Enables researchers to go
- beyond description and prediction
- beyond the identification of relationship, to at least a
partial determination of what causes them.

5. CHARACTERISTIC OF
EXPERIMENTAL RESEARCH

7. CONTROL OF EXTRANEOUS
VARIABLES
Researchers who conduct experimental studies try
to control any and all the subject characteristics.
There are some common ways that had been used
by researchers to minimize or eliminate threats

8. WAYS TO MINIMIZE OR ELIMINATE
THREATS
Randomization : assume the groups are equivalent
Holding certain variable constant : eliminate the possible
effects
Building the variable into design : include as distinct group
Matching : pairs subjects matched to certain variables
Using subjects as their own controls :compared the
performance
Using analysis of covariance : equate groups statistically on
the basis of pretest or other variables

9. GROUP DESIGNS IN
EXPERIMENTAL RESEARCH
Good designs control many of the various threats to
internal validity (chapter 9) while poor designs
control only a few.
The quality of an experiment depends on how well
the various threats to internal validity are controlled.

10. POOR EXPERIMENTAL DESIGNS

11. One-Shot Case Study Design
It does not provide for any comparison, so the
researcher cannot compare the treatment results (as
measured by the attitude scale) with the same group
before using the new textbook, or with those of
another group using a different textbook.
The researcher knows nothing about what the group
was like before using the text.

12. POOR EXPERIMENTAL DESIGNS

13. One-Group Pre test-Post test Design
 This design is better than the one-shot case study (the
researcher at least knows whether any change occur).
 Nine uncontrolled-for threats (history, maturation, instrument
decay, data collector characteristics, data collector bias,
testing, statistical regression, attitude of subjects, and
implementation).
 The researcher would not know if any differences between
pretest and posttest are due to the treatment or to one or
more of these threats.

14. TRUE EXPERIMENTAL DESIGNS
 The essential ingredient of a true experimental design is that
subjects are randomly assigned to treatment groups.
 Random assignment is a powerful technique for controlling the
subject characteristics threat to internal validity
 The randomized posttest-only control group design involves
two groups formed by random assignment.
 The randomized pretest-posttest control group design differs
from the randomized posttest-only control group design only in
the use of a pretest.

15. TRUE EXPERIMENTAL DESIGNS

16. TRUE EXPERIMENTAL DESIGNS

17. EVALUATING THE LIKELIHOOD OF
A THREAT
The important consideration in planning an
experimental study.
A number of possible threats may exist.
The must ask question by the research is : How
likely is it that any particular threat exist in this
study?

18. AID IN ASSESSING THE
LIKELIHOOD
Step 1 : What specific factors either are known to
affect the dependent variable or may logically to be
expected to affect this variable?
Step 2 : What is the likelihood of the comparison
groups differing on each of these factors?
Step 3 : Evaluate the threats on the basis of how
likely they are to have an effect, and plan to control
for them.

19. THREATS TO INTERNAL VALIDITY
Subject
characteristics
Mortality
Location
Instrumentation
Testing
History
Maturation
Attitude of Subjects
Regression
Implementation

20. CONTROL OF EXPERIMENTAL
TREATMENTS
Intended to improve the internal validity.
It has advantages and disadvantages.
The researcher control over the experimental
treatments- what, who, when and how of it.
Researchers seldom have control in educational
research.

21. QUESTIONS
1) What is experimental research?
2) What are the uniqueness of experimental research?
3) How does the experimental research differ from other
type of research?
4) What is random assignment, and what is the difference
between random assignment and random selection?
5) How to describe poor experimental design?