research design

research design

Consequently,  the research conducted by Yaun et al. did have some issues that  negatively impacted the internal validity of their research. Firstly,  convoluting variables were not adequately controlled. The exclusion  criteria consisted of cardiovascular disease, diabetes, hypertension,  renal disease, pulmonary disease, severe musculoskeletal aches, and  pregnancy. However, other significant variables such as age, gender,  marital status, educational level, or other medical issues. It is worth  noting that the diet and exercise habits of the participants were not  limited by the researchers.

Moreover,  the nurses in the experimental group worked a fixed schedule whereas  nurses in the control group worked alternating shifts. Secondly, the  lack of randomization coupled with the fact that the participants worked  for the same organization could have contaminated the results. Thirdly,  while the results of the research showed the exercise intervention  improved the physical fitness of the participants in the experimental  group, participants were not evaluated for musculoskeletal  improvements.

Recommendations to Strengthen Internal Validity

A  different research design would have strengthened internal validity.  Randomization is the most effective way to control individual  characteristics of participants. Randomization also eliminates for the  Hawthorne Effect, which occurs when participants behave differently  because they know they are being studied. Moreover, a cross-over design  is highly effective when groups are being compared to one another.  Although, this design is subject to carryover bias, in which an effect  carries over from one experimental condition to another (Polit &  Beck, 2017).

I  contend that a randomized control trial with a cross over design would  have increased the strength of the internal validity in this study. In a  cross-over design participants serve as their own control group, which  would negate the convoluting variables that influenced the results of  this study, and would more accurately gauge changes resulting from the  exercise intervention. I would also add a metric to assess the  musculoskeletal status of the participants. To limit the effects of  carryover bias, the health metrics of the participants would be obtained  before the exercise intervention to establish a baseline, then after  the exercise intervention, and finally, after a wash-out period, the  metrics should be re-recorded.

The Impact of Changes on Other types of Validity 

In  contrast to internal validity, statistical validity is not concerned  with the causal relationship between variables, but rather measures the  mathematical correlation of all relationships that occur between the  variables (Polit & Beck, 2017). The randomized control, crossover  design would improve statistical validity because the participants would  serve as their own control group making statistical analysis more  powerful. Construct validity determines if the outcome measured  corresponds to the theoretical construct of the study (Polit & Beck,  2017). In this research, the theoretical construct was Pender’s health  promotion model. Construct validity also would have been improved by  changing the design of the study. The same health promotion strategy  yields different outcomes for different participants based on individual  differences. The modification of the study’s design would have negated  these individual differences. External validity indicates if the results  of the research will remain the same when applied to other people or  settings (Polit & Beck, 2017). Again, a change in the design of this  research would optimize external validity which would increase the  likelihood of the results influencing evidence-based practice.

Failure to Consider Validity in Research