This document discusses quasi-experimental research designs. It defines quasi-experiments as resembling true experiments but lacking full control, such as random assignment. It describes various quasi-experimental designs including one group pre-test post-test, non-equivalent control group, interrupted time series, and time series with non-equivalent controls. Examples are provided of each design along with threats to validity. Common uses of quasi-experiments are discussed as well as advantages such as being able to be conducted in natural settings.

1. Quasi-Experimental Research Designs
Presented by
Asma Jabeen
M.Phil Psychology

2.  Quasi is
◦ “resembling”
 Quasi experiments involve procedures
that resemble those of true experiments.

3. Include intervention
or treatments but
lack degree of
“control”.
e.g. Lack of
Randomization

4. Why do we need quasi experiments
?

5. Types of Quasi Experiments
One group pre-test post-test design
Non equivalent control group design
Interrupted time series design
Time series with non-equivalent control
group designs

6.  One group pretest- post test design
represents a
pre- experimental design
 May be called a bad experiment
O1 X O2
e.g Children’s attitudes toward drugs.

8. History
Maturation
Testing
Instrumentation
Experimenter
expectancy effects
Novelty effects

9. Nonequivalent Control group
design(Campbell & Stanley,
1966)

11.  Manipulation of the independent variable
 Pretest for all of the comparison groups
 Posttest for all of the comparison groups
 No random assignment to the comparison
groups (which as you can imagine is
going to cause some problems with this
design as compared to the strong
“randomized” experimental designs.

12. It was hypothesized that
Environmental changes associated with old
age contribute, in part, to the feelings of
lose, inadequacy, and low self esteem
among the elderly.
Quasi experiment was carried out in
nursing home
Two groups were used one experimental
and one comparison group.

13.  Responsibility induced
condition.
 Participants were given
a plant to take care of
it(if they decided to
accept it).
 No responsibility
induced condition
 Participants were given
a plant (whether they
chose to have one or
not), nurses have to
take care of the plant

14.  Questionnaire were given that contained
the items related to “ how much control
they felt over general events in their life
and how happy and active they felt
(Langer & Rodin,1976)
 Ratings by staff members on traits e.g
alertness, sociability and activity.
 Posttest measure of social interest by a
competition
 So there was a list of dependent
variables perception of control happiness
, activity, interest level and so forth.

15. Results
 Residents in responsibility induced
group were more happier, active and
alert.
 Movie attendance favored
responsibility induced group
 10 residents from this group entered in
jelly bean competition but only one
from control group.

16. It was suggested that negative consequences of
aging can be reversed or reduced by giving the
elderly opportunity to make personal decisions
and to feel competent

17. Threats to the internal validity in non equivalent
control groups
(Langer and Rodin Study )
Non equivalent control group designs
generally control for all the major classes of
potential threats to the internal validity
excepts those due to additive effects of
 Selection-maturation
 Selection-history
 Selection-instrumentation
 Differential statistical regression
(Cook & Cambell, 1979).

18. External Validity
 Replication of the study is necessary
 One researcher must live with the fact that one
study is not likely to answer all questions about
a research hypothesis

19. Activity # 1

20. Interrupted time series design
 A time series is simply a set of
measurements of a variable taken at
various points in time.
 e.g mood of students during semester

21.  An interrupted time-series design, a time series
like this (the dependent variable) is interrupted
(usually near the middle) by the manipulation of
the independent variable.
O1 O2 O3 O4 O5 X O6 O7 O8 O9 O10
 multiple pretests
 a treatment (i.e., an intervention to be studied)
 multiple posttests
(Gribbons & Herman, 1997)

22. Graph showing effect of changing
paint color on students mood during
semester

23.  Simple interrupted time series design
can be used to assess the effect of a
treatment in a situation such as when
 A new product is introduced
 A new social reform is instituted
 Special advertising begun

24. Graph showing suspension of
license after reforms

25. Threats to internal validity and external validity

26. Time Series with Nonequivalent Control Group
 In a time series with nonequivalent
control group design, researchers make a
series of observations before and after
treatment for both a treatment group and a
comparable comparison group.
O1 O2 O3 O4 O5 X O6 O7 O8 O9 O10
------------------------------------------------
O1 O2 O3 O4 O5 O6 O7 O8 O9 O10

27. Activity#2

28.  Easy to conduct
 Lack of Randomization (no ethical concerns)
 Can be performed in natural settings
 Performed with groups
 Efficient in longitudinal study
 Provide comparisons ( treatment and control
groups)

29.  Potential for Non-Equivalent Groups
 Potential for Low Internal Validity

30. Researches
 Echabe, (2013) used quasi experiment to analyze the
effect of the catastrophe of Japan on previous
stereotypes about Japanese people sample, entitled
Stereotype, emotion, and behavior: a quasi-experiment
on the effects of Japan’s earthquake.
 Sample
 N= 238 adults
 Two phases of the study
 126 adults (month and a half to a week before earth
quake
 112 adults two weeks to month and a half after earth
quake.

31.  Participants were asked to indicate the extent to which they thought
 A)Japan was more powerful and influential in the world that their
own country
 B) had incompatible and conflicting political and economic goals
and interests relative to their own country or
 Participants were then asked to express their image (stereotype) of
Japanese people (warmth & competent)
 Participants were also asked to express their overall attitude
toward Japanese people

32.  the earthquake and its after-effects changed, at least temporarily,
their perception of the power of Japan and the compatibility
between its interests and those of participants’ own country.
 As a result, the stereotype of Japanese people became warmer but
less competent.
 The emotional reactions aroused by Japanese people became more
positive. After these events, participants felt more respect and
sympathy and less disdain and indifference.
 Finally, the participants manifested a stronger willingness for
cooperation and lower disposition toward competition and
avoidance

33. Cont…
Impact of legislation requiring moped and
motorbike riders to wear helmets (Balart & Riba 1995).
Research design
Interrupted time series design with non equivalent groups to
investigate the effect of these measures on the number of serious
injuries and number of deaths.
The results indicate a significant decrease in the number of serious
cases in the treated group (smaller motorcycles and mopeds) ,
which does not occur in the control group (larger motorcycles).

35. References
Ballart, X. & Riba , C. (1995). Impact of legislation requiring moped
and motorbike riders to wear helmets. Evaluation and Program
Planning,18 (4), 311-320
Campbell, D., & J. Stanley. (1963). Experimental and
quasi-experimental Designs. Chicago: Rand McNally.
Cook, T.D. & Campbell, D.T. (1979). Quasi-experimentation: design
and analysis issues for field settings. Retrieved from
http://books.google.com.pk/books/about/Quasi_experimentation.ht
ml?id=OKdEAAAAIAAJ&redir_esc=y
Echabe, A. E. (2013).Stereotype, emotion, and behavior: a
quasi-experiment on the effects of Japan’s earthquake. Journal of
Applied Social Psychology, 43, 2083–2089. doi:
10.1111/jasp.1216.

36. Referenes
Glass, G. V, Wilson, V. L., & Gottman, J. M. ( 1975). Design and
analysis of time-series experiments. Boulder, CO: Colorado
Associated University Press.
Gribbons, B., & Herman, J. (1997). True and quasi-experimental
designs. Practical Assessment, Research & Evaluation, 5(14).
Retrieved from http://PAREonline.net/getvn.asp?v=5&n=14
Shaughnessey, J. J., Zechmeister, E. B., & Zechmeister, J. S. (2012).
Research methods in Psychology. USA: McGraw-Hill company.