In Yuan et al. (2009), a study was conducted in order to “assess the effects of exercise intervention on nurses’ health-related physical fitness” (p. 1404). According to their methods, an intervention program was administered to nurses at a medical center in central Taiwan, surveying the nurses on their basic health information. As the intervention was conducted, the Labour’s Physical Fitness Test Method was used to measure the physical fitness of the nurses. A series of intense exercises were used that were nonetheless easy to perform and measure, through the use of measurement tools such as adjustable steps and other exercise equipment. The data was collected in a spreadsheet and measured using the statistical method, using paired t-tests to examine data and using ANCOVA to determine the effects of the intervention.
According to the textbook, internal validity “concerns the validity of inferences that, given that an empirical relationship exists, it is the independent variable, rather than something else, that caused the outcome” (p. 236). To that end, there is one potential concern related to the study of Yuan et al. (2009); for instance, the inference made is that the physical fitness of the nurses in question is related to their ability to complete the exercises set out in the study. It is entirely possible that the nurse’s physical fitness could be unrelated or ill-measured by the number of exercises performed in the study. Furthermore, it is possible that those nurses who are in the control group are equally as physically fit as those who do not perform the exercise intervention. Changes to the internal validity of the exercise could include encouraging the control group not to exercise on their own, to show the effects of sedentary lifestyle over this specific intervention. This would allow the other three forms of validity to hold greater water, as the correlation between exercise and non-exercise would be clearer. Nurses who fail to look at the validity of research studies may lend credence to less-credible studies when forming their opinions on diagnoses and treatments, which can be bad for patients.
References
Yuan, S., Chou, M., Hwu, L., Chang, Y., Hsu, W., & Kuo, H. (2009). An intervention program
