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Apply the scientific method to the information included within the scenario and develop a null and a research hypothesis based on it.

Applying the scientific method to develop a research hypothesis is an important step in the experimental design process. Prior to developing a hypothesis, first a question must be developed. Research question: What is the effect of incentives on students’ motivation to respond to posts? When a null hypothesis exists, the researcher is trying to discredit that there is not a statistical difference between the two variables stated in the hypothesis. Based on the scenario, my null hypothesis would be: incentives will not increase the number of online psychology students’ responses to posts. In addition, my research hypothesis would be: incentives will increase the number of online psychology students’ responses to posts.

Using the hypotheses you have developed, compare the characteristics of the different experimental research designs discussed in the Skidmore (2008) article and choose the one that is most appropriate to adequately test your hypotheses.

Skidmore (2008) discusses three various experimental research designs including: Pretest-Posttest-Only Control Group Design, Posttest-Only Control Group Design, and Solomon-Four Group Design. In the Pretest-Posttest-Only Control Group Design, participants are randomly assigned to two different groups. The experimental group receives incentives or assignments while the control group receives a different incentive or no incentive at all. A pretest occurs prior to implementing the incentive and then a measurement after the incentive is assigned is then conducted. Posttest-Only Control Group Design differs in that a pretest measurement does not exist, only a posttest to measure the incentive that has been applied however, all other characteristics are similar. Finally, the Solomon-Four Group Design contains all the characteristics of a Pretest-Posttest-Only Control Group Design, however, allows results to be compared amongst four groups with varying experiences. Thus, this design is considered to be the most powerful (Skidmore, 2018). Although this design is considered to be the most powerful amongst all the designs, it is complex, which can create challenges. All of these are considered true experiments.

Since the sample size is only 45 students, number of participants may not be large enough to conduct the Solomon-Four Group Design. Therefore, I would implement the Pretest-Posttest-Only Control Group Design test the hypothesis as the results. The design uses a pretest to measure prior to implementing the incentive thus it can be evaluated when incentives are implemented and not implemented after participating in a pretest. Finally, a post test can measure students’ responses and all the data can be compared.

Identify potential internal threats to validity and explain how you might mitigate these threats.

Internal threats are factors that may impact the ability for researchers to make conclusions about the study.  According to Skidmore (2018) ensuring that the independent variable caused the dependent variable may be concerning. Potential concerns include: bias or not using a randomized selection of participants, unclear about which variable occurred first, factors impacting the results, natural occurring changes, varying scores, participants not completing the entire study, influence of the testing on the results, changes that may have occurred, and the selection of participants may impact each group (Skidmore, 2018). In order to overcome these potential threats, it is important to examine if validity was noticed and decreased. Administering standardized tests or procedures may decrease the threat of instrumentation. Extreme test scores should not be the basis for assigning participants. A lengthy study could cause participants to dropout, so aiming to keep the study shorter may avoid this concern. Finally, randomizing participants and assignment to various groups when possible would also assist in avoiding internal threats.

Apply ethical principles to the proposed research and describe the implications of this type of research in terms of the population(s) and cultural consideration(s) represented in the sample(s) within the scenario.

According to Henrich, Heine & Norenzayan (2010) it is the responsibility of researchers to realize the differences amongst populations in order to refrain from bias as well as economic factors related to financial conclusions and anticipating certain outcomes. As with any study, researchers must uphold ethical standards and attempt to reduce harm, receive informed consent, and receive approval for the study. Researchers must be aware of cultural differences and respect diversity amongst participants. An online environment and virtual students, as discussed in the scenario, may encounter different challenges than a classroom environment where students are present. Thus, it is important for researchers to be aware of a virtual environment and respect diversity amongst students.


Henrich, J., Heine, S. J., & Norenzayan, A. (2010). Most people are not WEIRDNature, 466(7302), 29. doi: 10.1038/466029a

Skidmore, S. (2008). Experimental design and some threats to experimental validity: A primer (Links to an external site.)Links to an external site. (Links to an external site.)Links to an external site.. Paper presented at the Annual Meeting of the Southwest Educational Research Association (New Orleans, LA, February 6, 2008). Retrieved from the ERIC database in the Ashford University Library.

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