Read the article in Appendix D “Example of a Correlational Study” (Turner et al., 2016). Discuss the following questions related to the article found on ~ p. 177 under Critical Appraisal Criteria: 1. What quasi-experimental design is used in the study, and is it appropriate? 2. What does the author say about the limitations of the study? 3. What are the most common threats to internal and external validity? Cite any sources in APA format.
1. The quasi-experimental design used in the study conducted by Turner et al. (2016) is a “nonequivalent groups design.” This design is considered appropriate for this study as it involves two groups that are not randomly assigned, but rather naturally formed based on pre-existing characteristics or conditions. In this case, the study compares two groups of schools: those that implemented a violence prevention program and those that did not. The researchers could not randomly assign schools to the intervention and control groups as it was not feasible or ethical to do so. Therefore, the nonequivalent groups design allows for a comparative analysis between the two groups, taking into account pre-existing differences between them.
2. Turner et al. (2016) acknowledge several limitations in their study. Firstly, they highlight the potential for selection bias due to the nonrandom assignment of schools to the intervention and control groups. This may lead to differences between the groups other than the violence prevention program. Secondly, the authors note that generalizability may be limited as the study was conducted in a specific geographical area and involved only a specific type of violence prevention program. They also mention that the measures used to assess student behavior were collected through self-reports, which may introduce biases such as social desirability or recall errors. Finally, the authors mention that the duration of the study may not have been sufficient to observe long-term effects of the violence prevention program.
3. The most common threats to internal validity in the study by Turner et al. (2016) are related to the nonequivalent groups design used. Since schools were not randomly assigned to the intervention or control group, there may be pre-existing differences between the groups that could affect the outcome. Factors such as the socio-economic status of the students, the presence of other violence prevention programs, or the level of community support may differ between the groups. Therefore, it is important to carefully consider potential confounding variables in the analysis of the study results.
External validity refers to the generalizability of the study findings to other populations or settings. In the study by Turner et al. (2016), external validity may be limited due to the specific characteristics of the participating schools and the violence prevention program. The study was conducted in urban schools in a specific geographical area, and the violence prevention program implemented was also specific to that context. Therefore, caution must be exercised when applying the findings to schools in different settings or with different demographics.
To further support the discussion, it is important to consider additional scholarly sources. For example, in a study by Shadish, Cook, and Campbell (2002), they discuss the use of quasi-experimental designs and highlight their advantages and limitations. They emphasize that nonequivalent groups designs, such as the one used by Turner et al. (2016), are susceptible to selection biases due to nonrandom assignment. Another relevant source is Trochim and Donnelly’s (2008) book “The Research Methods Knowledge Base,” which provides a comprehensive overview of threats to internal validity and external validity in quasi-experimental designs. These sources would provide further insights into the appropriateness of the design and the potential limitations related to internal and external validity in Turner et al.’s (2016) study.
In conclusion, Turner et al. (2016) utilized a nonequivalent groups design in their correlational study, which was appropriate given the non-random assignment of schools to the intervention and control groups. However, this design introduces potential limitations in terms of internal validity, such as selection biases, and external validity, regarding generalizability to other populations or settings. The authors acknowledge these limitations, including selection bias, limited generalizability, reliance on self-report measures, and the short duration of the study. Considering additional scholarly sources, it is evident that these limitations are common in correlational research using nonequivalent group designs. Therefore, while the study provides valuable insights into the effectiveness of the violence prevention program, its findings should be interpreted with caution.