1. By: Sandra Hanson
May 27, 2013
Digital Media Presentation
Experimental Research Design

2. Experimental Design
History
 “Sir Ronald Fisher, a British statistician, first
developed the elements of experimental design
while at Rothamsted, Britain's oldest agricultural
experiment station, in the 1920s.
 In 1935, Fisher published „Design of Experiments,‟
a book that articulated the features of
experimental research design that are still used
today” (Hall).

3. Experimental Design
History continued
 “Experimental design expanded beyond its
agricultural experiment roots during World War II,
as the procedure became a method for assessing
and improving the performance of weapons
systems, such as long range artillery” (Hall).

4. Experimental Research Designs
Key Elements
 Definition: “test an idea (or practice or
procedure) to determine whether it influences an
outcome or dependent variable” (Creswell 295).
 Experimental Research Design is used when a
researcher wants to establish a cause and effect
between a independent and dependent
variables (Creswell 295).

5. Experimental Design
Six Major Factors
 Random assignment
 Control over extraneous variables
 Manipulation of the treatment conditions
 Outcome measures
 Group comparisons
 Threats to validity

6. Experimental Design
Examples
Between Group Designs
True experiments (pre- and posttest, posttest only)
Quasi-experiments (pre- and posttest, posttest
only)
Factorial designs
Within Group or Individual Designs
Time series experiments (interrupted, equivalent)
Repeated measures experiments
Single subject experiments

7. Experimental Design
Ethical Issues
 Withholding the experimental treatment from
some individuals who might benefit.
 Overlooks the potential of some individuals for
beneficial treatment.
 When to conclude an experiment; whether the
experiment will provide the best answers to a
problem, and considerations about the stakes
involved in conducting the experiment.

8. Experimental Design
Conducting the Research Steps (8)
1. Decide if an experiment addresses the
research problem.
2. Form a hypothesis to test cause-and-effect
relationships.
3. Select an experimental unit and identify study
participants.
4. Select an experimental treatment and
introduce it.

9. Experimental Design
Conducting the Research Steps (8)
continued
5. Choose a type of experimental design.
6. Conduct the experiment.
7. Organize and analyze the data.
8. Develop an experimental research report.

10. Experimental Design
Evaluation from Bausell (1994)
 The experiment has a powerful intervention.
 The treatment groups are few in number.
 Participants will gain from the intervention.
 The researcher derives the number of
participants per group in some systematic way.

11. Experimental Design
Evaluation from Bausell (1994)
continued
 An adequate number of participants were
used in the study.
 The researcher uses measures and
observations that are valid, reliable, and
sensitive.
 The researcher controls for extraneous factors
that might influence the outcome.
 The researcher addresses threats to internal
and external validity.

12. Experimental Design
Advantages and Disadvantages
 “The major advantage of an experimental
design is that, if properly conducted, it can
demonstrate causality” (Price).

13. Experimental Design
Advantages and Disadvantages
continued
 “While experiments are quite useful for
demonstrating cause and effect relationships,
they suffer from some major disadvantages.
First, good experiments are difficult to conduct.
They require a lot of human energy and
resources” (Price).

14. Experimental Design
Advantages and Disadvantages
continued
 “Second, it takes a lot of ingenuity, cleverness,
and experience to design experiments well.
Third, experiments often take the behavior we
are interested in out of context. This sometimes
produces considerable artificiality and some
question how readily we can generalize any
findings to other contexts” (Price).

15. References
 Creswell, John W. (2012). Educational research:
Planning, conducting, and evaluating quantitative
and qualitative research (4th ed.). Boston, MA.
Pearson Education, Inc.
 Hall, Shane. The History of Experimental Design;
How Contributor, 1999-2013 Demand Media, Inc.
 Penelo‟s Theme http://www.last.fm/music/+free-
music-downloads/classical
 Price, Ian. copyright 2000 University of New
England, Armidale, NSW, 2351.