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.
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.
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.
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.
17. EVALUATING THE LIKELIHOOD OF
A TRHREAT
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?
