Slides of the book 'Research Methods for Business' A Skill Building Approach By Authors Uma Sekaran and Roger Bougie

1. Chapter 7
EXPERIMENTAL DESIGNS

2. Types of Experimental Designs
• Non-experimental
– Post-test only
– Pre-post test
• Experimental
– Pre & post-test with control group
– Pre & multiple post-test with control group
– After-only control group
– Solomon four-group
• Quasi
– Non-equivalent control group
– Simple time-series
– Multiple time series

3. Laboratory vs. Field Experiments
• Lab
– Artificial (Low external validity)
– Control of variables (High internal validity)
– Good for theory building and process-level
understanding
• Field
– Realistic (High external validity)
– Less control (Low internal validity)
– Good for program evaluation

4. Non-Experimental
• No control group
• No measurement of dependent variable
before intervention
• Referred to as quasi-experiment in
Sekaran

5. Non-Experimental
• Post-test only
– Referred to as quasi-experiment in Sekaran
– Measurement taken only after intervention
– No baseline measure taken
– Hard to determine if change
• has occurred
• is due to intervention
– Good for studying nature of intervention
– Useful for evaluating participant learning after a
training session
Intervention Post-measure

6. Non-Experimental
• Pre-test/post-test
– Referred to as quasi-experiment in
Sekaran
– Change inferred from differences in pre vs.
post intervention measures
Intervention Post-measurePre-measure

7. Non-Experimental
• Pre-test/post-test
– Is affected by testing, instrumentation,
history, time, maturation, & statistical
regression effects
– Use internal referencing data to test
whether only relevant var changed and
irrelevant var did not change following
intervention
Intervention Post-measurePre-measure

8. Experimental
• Control group
• Random assignment of participants to
conditions
– Is the study described in the ethnic identity
paper (Kim & Gelfand) an experiment? Why
or Why not?

9. Experimental
• Pre-test/post-test w/control group
Intervention Post-measurePre-measure
Post-measurePre-measure
Experimental group
Control group
• Subject to mortality threats

10. Experimental
• Pre-test/post-test w/control group (omnibus
test= repeated measures anova)
– Experimental group should be ‘better’ than
control group on post-test measures (t-test
independent groups)
– Experimental group scores should “improve”
from pre to post-test (t-test paired)
– Control group scores should not change from pre
to post-test (t-test paired)
– Should be no group differences on pre-test
measures esp on matching variables if random
assignment was not possible (t-test independent
groups)

11. • Pre-test & Post-test Control Group with
multiple post-test measures
Experimental
Intervention Post-measure 1,2,3Pre-measure
Post-measure 1,2,3Pre-measure
Experimental group
Control group
– Tests long and short term effects of
intervention (e.g., training)

12. • Pre-test & Post-test Control Group with
multiple post-test measures (adapted to
org’n stakeholders’ needs)
Experimental
Intervention Post-measure 1Pre-
measure
Experimental group
Control group
Control Post-
measure 2
Control Post-measure 1
Pre-
measure
Intervention
Post-
measure 2

13. Experimental
• After only control group
Intervention Post-measure
Post-measure
Experimental group
Control group
• Eliminates testing effects found in pre-test post-test
control group design
• Classified as quasi-experimental in Sekaran
• Referred to as post-tests only with experimental &
control groups in Sekaran
• Subject to Selection & mortality threats

14. • Solomon Four-group design
Experimental
Intervention Post-measurePre-measure
Post-measurePre-measure
Experimental group
Control group
Intervention Post-measure
Post-measure
Experimental group
Control group

15. TABLE 7.2Copyright © 2003 John Wiley & Sons, Inc. Sekaran/RESEARCH 4E

16. Types of Experimental Designs
• Experimental
– Pre & post-test with control group
– Pre & multiple post-test with control group
– After-only control group
– Solomon four-group
• Quasi
– Non-equivalent control group
– Simple time-series
– Multiple time series

17. Quasi-Experimental
• Non-equivalent control group
– E.g., training conditions assigned to pre-
existing groups
– Gather pre-intervention data on important
control variables.
– Use pre-measure as a statistical control in
the analyses for differences in post-
intervention measures

18. • Simple time-series design
Quasi-Experimental
Intervention Post-measure 1,2,3Pre-measure 1, 2, 3
• Pre-measures should not be different from
each other
• Post measures should not be different from
each other
• Pre vs. post measures should be different
from each other

19. • Multiple time-series design
Quasi-Experimental
Intervention Post-measure 1,2,3Pre-measure 1, 2, 3
Post-measure 1,2,3Pre-measure 1, 2, 3
Control group
Experimental group
• Same conditions as simple time series design
plus..
• Pre and post measures of control group should
not differ from each other
• Limitations: Testing effects, instrumentation
problems

20. Types of Experimental Designs
• Non-experimental
– Post-test only
– Pre-post test
• Experimental
– Pre & post-test with control group
– Pre & multiple post-test with control group
– After-only control group
– Solomon four-group
• Quasi
– Non-equivalent control group
– Simple time-series
– Multiple time series