Essay Sample on the Validity of Quantitative Quasi-Experimental Research Design

The validity of a research design is essential as it seeks to assess the quality of a research report. This term refers to whether the various research tools applied accurately measure the parameters that it intended to. In particular, the quasi-experimental study faces both internal and external validity threats (Campbell et al. 2015). This paper focuses on the study of an intervention that promotes health fitness among nurses. Several issues are arising as discussed below.

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Internal validity refers to the existence of a causal relationship within the study sample when all external factors are held constant (Apel, 2015). This study compromises the internal validity. Firstly, the natural changes of the participants may adversely impact the research. Using steeper stairs three times a week for three months may become routine and monotonous leading to boredom, tiredness, and fatigue. The participants may stop participating in the study without the knowledge of the researchers. Therefore, erroneous data is collected every week from these participants.

Another threat to internal validity is the history of the test subjects that have a significant effect on key variables of the research. This threat is evident in the study where participants are left alone to fill out the questionnaire which seeks to get information on the study's critical auxiliary variables. The participants can easily lie when providing this information because of lack of supervision or an alternative source of validating this information.

On the other hand, external validity refers to the extent to which the study subject results reflect the underlying conditions of the entire objects under study. The nonrandom selection of subjects is a significant factor that undermines external validity (Johnston et al. 2015). All nurses were selected from the same hospital thereby limiting the geographical sample size. In addition to this, the selection was based on the willingness of these nurses to participate in the study as opposed to scientific selection methods. This does not only increase the statistical error but also reduces the confidence level of the results. Consequently, the probability of having different results from the sample had the census approach been undertaken increases.

The absence of a pre-test in this study also compromises external validity. Both the control and experimental group are exposed to the intervention right away without a pre-test to establish the initial state of these subjects. Despite the state of the control group remaining unchanged over time, it becomes difficult to assess the changes of the experimental group during the study period if there is no stable initial state. Every research design has validity threats, and therefore the researcher should come up with ways that will reduce these threats to a minimum level and maximize the validity.

References

Campbell, D. T., & Stanley, J. C. (2015). Experimental and Quasi-experimental Designs for Research. Ravenio Books.

Kennedy-Martin, T., Curtis, S., Faries, D., Robinson, S., & Johnston, J. (2015). A Literature Review on the Representativeness of Randomized Controlled Trial Samples and Implications for the External Validity of Trial Results. Trials, 16(1), 495.

Siegmund, J., Siegmund, N., & Apel, S. (2015, May). Views on Internal and External Validity in Empirical Software Engineering. In Software Engineering (ICSE), 2015 IEEE/ACM 37th IEEE International Conference on (Vol. 1, pp. 9-19). IEEE.