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Experimental Design Assessment







Experimental Design Assessment





If the classical experimental design appropriate

Yes, the classical experimental design was the right experimental design to test an assumption that neighborhood disorders lead to higher crime rates as one cares about the neighborhood.

The classical experimental design states that to effect such type of experimenting effectively, various factors are used, such as randomly selection groups, an experimental, a control group, pretest group, and post-test group (Hoefler, González-Barrios, Bhatta, Nunes, Berro, Nalin & Gutierrez, 2020). All the factors were met in this experiment, from random selection to dividing the group into two, and pretest and post-test are done. With classical experimental design appropriately applied, it provided an opportunity to test for the hypothesis. The hypothesis required using different environments organized and disorganized (clean and dirty bathroom); use of various categories of people to understand how they responded to both the environments effectively.

In the design, the students were directed to visit the bathrooms at different times, thereby eliminating the possibility of interacting. Otherwise, interactions would have diminished their validity. Similarly, first-year students who had recently changed environments were picked. A change of environment like urbanization is one of the ways to test reactions to the environment.

Threats to validity associated with experimental design

  1. Testing – both the groups were tested by being directed to the clean bathrooms first. By virtue, taking them to a dirty bathroom next time would trigger them that something is not necessarily right. For instance, they might act inexpertly by putting a few scattered things in order or wiping splashed water.
  2. Diffusion of treatment – both groups are randomly selected irrespective of their classrooms. There is a chance the control and experimental two groups would communicate and share what was discussed.
  3. Experimental expectancy – during the group's involvement, the researcher may have left a clue of what is expected unknowingly. In the process, the students may already know what is expected and therefore act differently.
  4. Selection – before any treatment, the groups may be disparate and not comparable in any way. Anyone may uniquely act without any effect from their environment as well.

What I would have done differently

To eliminate experimental expectancy and testing validity threats that can be acquired during the initial visit with experimental design, I would have only designed a two-group post-test only design.

This scenario was randomly assigned to 30 newcomers and then divided into two control and experimental groups. At break time, the students are then directed to the bathrooms, controlling the clean one and experimental group to the dirty group.

It is expected the students' true nature will exhibit on the first go. The criminal ones will leave splashed water unwiped if their environments cause them to do so. On the other hand, the other type will clean the water even if it is not influencing. However, with disorganization, it is expected that that student in the clean bathrooms will leave them clean while the other group dirty.

This experimental design beats some of the validity threats found in classical experimental design. For instance, there is a chance the students will expect an outcome during their initial visit (testing); to eliminate this prejudice, there is no testing but post-test alone. Similarly, diffusion might occur in the experimental design, where students might discuss during their time in class. In the Two-group post-test only design, the students have no time to do so.




Hoefler, R., González-Barrios, P., Bhatta, M., Nunes, J. A., Berro, I., Nalin, R. S., & Gutierrez, L. (2020). Do spatial designs outperform classic experimental designs? Journal of Agricultural, Biological and Environmental Statistics25(4), 523-552.



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