BUSIESS

1. Dr. Sasmita Mishra
Experimental Design

2. What is an experiment?
 An experiment is generally used to infer a
causality.
 In an experiment, a researcher actively
manipulates one or more causal variables and
measures their effects on the dependent
variable of interest.

3. Necessary Conditions for Making
Causal Inferences
 Concomitant variation
 Time order of occurrence of variables
 Elimination of other possible causal
factors

4. Purchase of Fashion Clothing
Education High Low Total
High 363 (73) 137(27) 500
Low 322(64) 178(36) 500
Low income High income
Purchase Purchase
Educatio
n
High Low Total Education High Low Total
High 122(6
1)
78 (39) 200 High 241(8
0)
59(20) 300
Low 171
(57)
129(43) 300 Low 151(7
6)
49(24) 200

5. Concomitant variation
 Suppose there is a positive relationship
between the quality of dealers and
market share.
H: The success of a company’s marketing
efforts is highly dealer dependent.
 Where the company has good dealers, it
has market penetration and where the
company has poor dealers, the
company has unsatisfactory market
penetration.

6. Concepts Used in Experiments
 Independent Variable
 Test Unit
 Dependent variables
 Experiment
 Extraneous variable

7. Validity in experiments
 External Validity
 Internal Validity

8. Extraneous variables:
 History (outside economic effect-affects internal validity)
 Maturity (passage of time-affects internal validity)
 Instrumentation (measuring instrument changes-affects
internal validity)
 Selection Bias (improper assignment of test units to
treatment-affects internal validity)
 Mortality (loss of test units-affects internal validity)
 Statistical regression (test unit with extreme score move
closer to average score during course of experiment-
affects internal validity)
 Testing effects:
-Main effect: prior observation affects later observation-
affects internal validity)
-Interactive effect: prior measurement affects test unit
response to independent variable-affects external validity)

9. Methods to Control Extraneous
Variables
 Randomization
 Matching
 Use of experimental designs
 Statistical control

10. Environments of Conducting
Experiments
 Field Experiment
 Laboratory Experiment

11. A Classification of Experimental
Designs

12. Pre-experimental design
Pre-experimental designs do not make use of any
randomization procedures to control the extraneous
variables. Therefore, the internal validity of such
designs is questionable.
 One-shot case study:
X O
 One-group pre-test–post-test design:
O1 X O2
 Static group comparison:
Group 1 - X O1
Group 2 - O2

13. Quasi-experimental designs
In quasi-experimental design, the researcher can
control when measurements are taken and on
whom they are taken. However, this design lacks
complete control of scheduling of treatment and
also lacks the ability to randomize test units’
exposure to treatments.
 Time series design:
O1 O2 O3 O4 X O5 O6 O7 O8
Contd…..

14. Quasi-experimental designs

15. Quasi-experimental designs
 Multiple time series design:
Experimental Group: O1 O2 O3 O4 X O5 O6 O7 O8
Control Group: O′1 O′2 O′3 O′4 O′5 O′6 O′7 O′8

16. True experimental designs
In true experimental designs, researchers can
randomly assign test units as well as random
treatments to an experimental group. Here, the
researcher is able to eliminate the effect of
extraneous variables from both the experimental
and control group.
 Pre-test–post-test control group:
Experimental Group: R O1 X O2
Control Group: R O3 O4

17. True experimental designs
 Post-test – only control group design:
Experimental Group: R X O1
Control Group: R O2
 Solomon four-group design:
Experimental Group 1 : R O1 X O2
Control Group 1: R O3 O4
Experimental Group 2: R X O5
Control Group 2: R O6

18. Identifying treatment effect
 O2-O1= TE + extraneous without interactive testing +
interactive testing……………………(i)
 O4-O3= Testing E + extraneous without interactive
testing….(ii)
 O5-O1= Testing E+ TE + extraneous without
interactive testing…(iii)
 O5-O3=TE + Extraneous factor without testing
effect…(iv)
 O6-O1= Extraneous factor without testing effect…(v)
 O6-O3= Extraneous factor without testing effect…(vi)
 O6- O1+O3 = Extraneous factor without testing
effect…(vii)
 2
 O5- O1+O3 = Treatment effect +Extraneous factor without testing
effect…(viii)
 2
 (vii)-(viii) = Treatment Effect

19. Factors Affecting External
Validity
 The environment at the time of test may be
different from the environment of the real world
where these results are to be generalized.
 Population used for experimentation of the test
may not be similar to the population where the
results of the experiments are to be applied.
 Results obtained in a 5–6 week test may not hold
in an application of 12 months.
 Treatment at the time of the test may be different
from the treatment of the real world.

20. Internal validity
History: events taking place at the same time as the
experiment is underway
Pre-testing: errors arising from the process of taking "before" and
"after" measures from the same sample as that
providing "after" measures
Maturation: biological and/or psychological changes in participants
Instrumentation: changes in the calibration of measurement
instruments, questionnaires, interviewers or
interviewing technique
Sampling bias: assignment of participants to experimental groups in a
way likely to prejudice outcomes
Mortality: differential loss of participants from experimental
groups
External validity
Interactive effects of testing: pre-exposure measurements going rise to heightened
awareness
Interactive effects of sampling
bias:
non-random assignment of participants to
experimental groups leading to differing responses to
the experimental treatment
Contrived situations: experimental setting elicits responses that differ from
those which would be obtained in the real world

21. Statistical designs
Statistical designs allow for statistical
control and analysis of external variables.
 Completely randomized design
 Randomized block design
 Latin square design
 Factorial design

22. Completely randomized design
Commercial A Commercial B Commercial C
A B C
A B C
A B C
A B C
A B C
A B C
A B C
A B C
A B C

23. Randomized Block Design
Block
No.
Store
Patronage
Treatment Groups
Commercial A Commercial
B
Commercial
C
1 Heavy A B C
2 Medium A B C
3 Low A B C
4 None A B C

24. Latin Square Design
Store
Patronage
Interest in Store
High Medium Low
High B A C
Medium C B A
Low A C B

25. Factorial Design
Amount of
Store
Information
Amount of Humour
No Humour Medium Humour High Humour
Low A B C
Medium D E F
High G H I

26. Assignment
 In one experiment there are two experimental
treatments, that is, teaching through co-operative
learning and teaching through lecture method. It
is observed that there may be differential effects
of these methods on different levels of
intelligence of the students. On the basis of the
IQ score the experimenter divides the students
into two groups: one high intelligent group and
the other the low intelligent group. There are four
groups of students within each of the two levels of
intelligence.
 Identify the experimental design.

27. Class Assignment
 One beverage company wants to launch a new
soft drink in the market. To finalize the appropriate
taste for the drink, the company wants to
compare three shortlisted varieties of taste for the
soft drink. As a researcher, design an experiment
to obtain the above information. Prepare the
complete layout of the experimental design,
mention the independent, dependent and
extraneous variables, objectives and hypotheses
of the study, process of administration of
treatments, selection of sample, and time frame
of the study. Also mention to what extent you
have been successful to maintain the internal and

28. Class Assignment
 One of your friend had arranged a drawing
competition for students in front of a store and
wants to know its impact on the foot fall.
 Which research design you would adopt here?
 What are your Ivs and DVs
 What threats to internal validity you perceive
here?

29. Thank You